diff --git a/application/MainWindow.cpp b/application/MainWindow.cpp
index 1633cc39..ef758fae 100644
--- a/application/MainWindow.cpp
+++ b/application/MainWindow.cpp
@@ -534,7 +534,7 @@ MainWindow::MainWindow(QWidget *parent) : QMainWindow(parent), ui(new MainWindow
 			auto meta = Env::getInstance().metacache()->resolveEntry("skins", profile.id + ".png");
 			auto action = CacheDownload::make(QUrl("https://" + URLConstants::SKINS_BASE + profile.id + ".png"), meta);
 			skin_dls.append(action);
-			meta->stale = true;
+			meta->setStale(true);
 		}
 	}
 	if (!skin_dls.isEmpty())
@@ -1028,7 +1028,7 @@ InstancePtr MainWindow::instanceFromZipPack(QString instName, QString instGroup,
 	{
 		const QString path = url.host() + '/' + url.path();
 		auto entry = ENV.metacache()->resolveEntry("general", path);
-		entry->stale = true;
+		entry->setStale(true);
 		CacheDownloadPtr dl = CacheDownload::make(url, entry);
 		NetJob job(tr("Modpack download"));
 		job.addNetAction(dl);
diff --git a/application/handlers/WebResourceHandler.cpp b/application/handlers/WebResourceHandler.cpp
index 5e51584b..757b870a 100644
--- a/application/handlers/WebResourceHandler.cpp
+++ b/application/handlers/WebResourceHandler.cpp
@@ -13,7 +13,7 @@ WebResourceHandler::WebResourceHandler(const QString &url)
 	: QObject(), m_url(url)
 {
 	MetaEntryPtr entry = ENV.metacache()->resolveEntry("icons", url);
-	if (!entry->stale)
+	if (!entry->isStale())
 	{
 		setResultFromFile(entry->getFullPath());
 	}
diff --git a/application/pages/global/AccountListPage.cpp b/application/pages/global/AccountListPage.cpp
index 84d317c1..89b853c5 100644
--- a/application/pages/global/AccountListPage.cpp
+++ b/application/pages/global/AccountListPage.cpp
@@ -133,7 +133,7 @@ void AccountListPage::addAccount(const QString &errMsg)
 			auto action = CacheDownload::make(
 				QUrl("https://" + URLConstants::SKINS_BASE + profile.id + ".png"), meta);
 			job->addNetAction(action);
-			meta->stale = true;
+			meta->setStale(true);
 		}
 
 		job->start();
diff --git a/depends/launcher/org/multimc/onesix/OneSixLauncher.java b/depends/launcher/org/multimc/onesix/OneSixLauncher.java
index d94d06b0..0d1e2174 100644
--- a/depends/launcher/org/multimc/onesix/OneSixLauncher.java
+++ b/depends/launcher/org/multimc/onesix/OneSixLauncher.java
@@ -31,6 +31,8 @@ public class OneSixLauncher implements Launcher
 	// parameters, separated from ParamBucket
 	private List<String> libraries;
 	private List<String> extlibs;
+	private List<String> extlibs32;
+	private List<String> extlibs64;
 	private List<String> mcparams;
 	private List<String> mods;
 	private List<String> jarmods;
@@ -38,7 +40,7 @@ public class OneSixLauncher implements Launcher
 	private List<String> traits;
 	private String appletClass;
 	private String mainClass;
-	private String natives;
+	private String nativePath;
 	private String userName, sessionId;
 	private String windowTitle;
 	private String windowParams;
@@ -54,7 +56,22 @@ public class OneSixLauncher implements Launcher
 	private void processParams(ParamBucket params) throws NotFoundException
 	{
 		libraries = params.all("cp");
-		extlibs = params.all("ext");
+		extlibs = params.allSafe("ext", new ArrayList<String>());
+		extlibs32 = params.allSafe("ext32", new ArrayList<String>());
+		extlibs64 = params.allSafe("ext64", new ArrayList<String>());
+
+		// Unify the extracted native libs according to actual system architecture
+		String property = System.getProperty("os.arch");
+		boolean is_64 = property.equalsIgnoreCase("x86_64") || property.equalsIgnoreCase("amd64");
+		if(is_64)
+		{
+			extlibs.addAll(extlibs64);
+		}
+		else
+		{
+			extlibs.addAll(extlibs32);
+		}
+
 		mcparams = params.allSafe("param", new ArrayList<String>() );
 		mainClass = params.firstSafe("mainClass", "net.minecraft.client.Minecraft");
 		appletClass = params.firstSafe("appletClass", "net.minecraft.client.MinecraftApplet");
@@ -62,7 +79,7 @@ public class OneSixLauncher implements Launcher
 		jarmods = params.allSafe("jarmod", new ArrayList<String>());
 		coremods = params.allSafe("coremod", new ArrayList<String>());
 		traits = params.allSafe("traits", new ArrayList<String>());
-		natives = params.first("natives");
+		nativePath = params.first("natives");
 
 		userName = params.first("userName");
 		sessionId = params.first("sessionId");
@@ -95,7 +112,7 @@ public class OneSixLauncher implements Launcher
 		Utils.log();
 
 		Utils.log("Native path:");
-		Utils.log("  " + natives);
+		Utils.log("  " + nativePath);
 		Utils.log();
 
 		Utils.log("Traits:");
@@ -343,16 +360,13 @@ public class OneSixLauncher implements Launcher
 
 		// extract native libs (depending on platform here... java!)
 		Utils.log("Preparing native libraries...");
-		String property = System.getProperty("os.arch");
-		boolean is_64 = property.equalsIgnoreCase("x86_64") || property.equalsIgnoreCase("amd64");
 		for(String extlib: extlibs)
 		{
 			try
 			{
-				String cleanlib = extlib.replace("${arch}", is_64 ? "64" : "32");
-				File cleanlibf = new File(cleanlib);
-				Utils.log("Extracting " + cleanlibf.getName());
-				Utils.unzipNatives(cleanlibf, new File(natives));
+				File extlibf = new File(extlib);
+				Utils.log("Extracting " + extlibf.getName());
+				Utils.unzipNatives(extlibf, new File(nativePath));
 			} catch (IOException e)
 			{
 				System.err.println("Failed to extract native library:");
@@ -365,9 +379,9 @@ public class OneSixLauncher implements Launcher
 		// set the native libs path... the brute force way
 		try
 		{
-			System.setProperty("java.library.path", natives);
-			System.setProperty("org.lwjgl.librarypath", natives);
-			System.setProperty("net.java.games.input.librarypath", natives);
+			System.setProperty("java.library.path", nativePath);
+			System.setProperty("org.lwjgl.librarypath", nativePath);
+			System.setProperty("net.java.games.input.librarypath", nativePath);
 			// by the power of reflection, initialize native libs again. DIRTY!
 			// this is SO BAD. imagine doing that to ld
 			Field fieldSysPath = ClassLoader.class.getDeclaredField("sys_paths");
diff --git a/logic/CMakeLists.txt b/logic/CMakeLists.txt
index 62a4e738..19236e1b 100644
--- a/logic/CMakeLists.txt
+++ b/logic/CMakeLists.txt
@@ -284,9 +284,6 @@ set(LOGIC_SOURCES
 	minecraft/forge/ForgeVersion.cpp
 	minecraft/forge/ForgeVersionList.h
 	minecraft/forge/ForgeVersionList.cpp
-	minecraft/forge/ForgeMirror.h
-	minecraft/forge/ForgeMirrors.h
-	minecraft/forge/ForgeMirrors.cpp
 	minecraft/forge/ForgeXzDownload.h
 	minecraft/forge/ForgeXzDownload.cpp
 	minecraft/forge/LegacyForge.h
diff --git a/logic/minecraft/Library.cpp b/logic/minecraft/Library.cpp
index 9a1d2cc7..922db84e 100644
--- a/logic/minecraft/Library.cpp
+++ b/logic/minecraft/Library.cpp
@@ -1,59 +1,178 @@
 #include "Library.h"
+#include <net/CacheDownload.h>
+#include <minecraft/forge/ForgeXzDownload.h>
+#include <Env.h>
 #include <FileSystem.h>
 
-QStringList Library::files() const
+void Library::getApplicableFiles(OpSys system, QStringList& jar, QStringList& native, QStringList& native32, QStringList& native64) const
 {
-	QStringList retval;
-	QString storage = storageSuffix();
-	if (storage.contains("${arch}"))
+	auto actualPath = [&](QString relPath)
 	{
-		QString cooked_storage = storage;
-		cooked_storage.replace("${arch}", "32");
-		retval.append(cooked_storage);
-		cooked_storage = storage;
-		cooked_storage.replace("${arch}", "64");
-		retval.append(cooked_storage);
-	}
-	else
-		retval.append(storage);
-	return retval;
-}
-
-bool Library::filesExist(const QDir &base) const
-{
-	auto libFiles = files();
-	for(auto file: libFiles)
+		QFileInfo out(FS::PathCombine(storagePrefix(), relPath));
+		return out.absoluteFilePath();
+	};
+	if(m_mojangDownloads)
 	{
-		QFileInfo info(base, file);
-		qWarning() << info.absoluteFilePath() << "doesn't exist";
-		if (!info.exists())
-			return false;
-	}
-	return true;
-}
-
-QString Library::url() const
-{
-	if (!m_absolute_url.isEmpty())
-	{
-		return m_absolute_url;
-	}
-
-	if (m_base_url.isEmpty())
-	{
-		return QString("https://" + URLConstants::LIBRARY_BASE) + storageSuffix();
-	}
-
-	if(m_base_url.endsWith('/'))
-	{
-		return m_base_url + storageSuffix();
+		if(m_mojangDownloads->artifact)
+		{
+			auto artifact = m_mojangDownloads->artifact;
+			jar += actualPath(artifact->path);
+		}
+		if(!isNative())
+			return;
+		if(m_nativeClassifiers.contains(system))
+		{
+			auto nativeClassifier = m_nativeClassifiers[system];
+			if(nativeClassifier.contains("${arch}"))
+			{
+				auto nat32Classifier = nativeClassifier;
+				nat32Classifier.replace("${arch}", "32");
+				auto nat64Classifier = nativeClassifier;
+				nat64Classifier.replace("${arch}", "64");
+				auto nat32info = m_mojangDownloads->getDownloadInfo(nat32Classifier);
+				if(nat32info)
+					native32 += actualPath(nat32info->path);
+				auto nat64info = m_mojangDownloads->getDownloadInfo(nat64Classifier);
+				if(nat64info)
+					native64 += actualPath(nat64info->path);
+			}
+			else
+			{
+				native += actualPath(m_mojangDownloads->getDownloadInfo(nativeClassifier)->path);
+			}
+		}
 	}
 	else
 	{
-		return m_base_url + QChar('/') + storageSuffix();
+		QString raw_storage = storageSuffix(system);
+		if(isNative())
+		{
+			if (raw_storage.contains("${arch}"))
+			{
+				auto nat32Storage = raw_storage;
+				nat32Storage.replace("${arch}", "32");
+				auto nat64Storage = raw_storage;
+				nat64Storage.replace("${arch}", "64");
+				native32 += actualPath(nat32Storage);
+				native64 += actualPath(nat64Storage);
+			}
+			else
+			{
+				native += actualPath(raw_storage);
+			}
+		}
+		else
+		{
+			jar += actualPath(raw_storage);
+		}
 	}
 }
 
+QList<NetActionPtr> Library::getDownloads(OpSys system, HttpMetaCache * cache, QStringList &failedFiles) const
+{
+	QList<NetActionPtr> out;
+	bool isLocal = (hint() == "local");
+	bool isForge = (hint() == "forge-pack-xz");
+
+	auto add_download = [&](QString storage, QString dl)
+	{
+		auto entry = cache->resolveEntry("libraries", storage);
+		if (!entry->isStale())
+			return true;
+		if(isLocal)
+		{
+			QFileInfo fileinfo(entry->getFullPath());
+			if(!fileinfo.exists())
+			{
+				failedFiles.append(entry->getFullPath());
+				return false;
+			}
+			return true;
+		}
+		if (isForge)
+		{
+			out.append(ForgeXzDownload::make(storage, entry));
+		}
+		else
+		{
+			out.append(CacheDownload::make(dl, entry));
+		}
+		return true;
+	};
+
+	if(m_mojangDownloads)
+	{
+		if(m_mojangDownloads->artifact)
+		{
+			auto artifact = m_mojangDownloads->artifact;
+			add_download(artifact->path, artifact->url);
+		}
+		if(m_nativeClassifiers.contains(system))
+		{
+			auto nativeClassifier = m_nativeClassifiers[system];
+			if(nativeClassifier.contains("${arch}"))
+			{
+				auto nat32Classifier = nativeClassifier;
+				nat32Classifier.replace("${arch}", "32");
+				auto nat64Classifier = nativeClassifier;
+				nat64Classifier.replace("${arch}", "64");
+				auto nat32info = m_mojangDownloads->getDownloadInfo(nat32Classifier);
+				if(nat32info)
+					add_download(nat32info->path, nat32info->url);
+				auto nat64info = m_mojangDownloads->getDownloadInfo(nat64Classifier);
+				if(nat64info)
+					add_download(nat64info->path, nat64info->url);
+			}
+			else
+			{
+				auto info = m_mojangDownloads->getDownloadInfo(nativeClassifier);
+				if(info)
+				{
+					add_download(info->path, info->url);
+				}
+			}
+		}
+	}
+	else
+	{
+		QString raw_storage = storageSuffix(system);
+		auto raw_dl = [&](){
+			if (!m_absoluteURL.isEmpty())
+			{
+				return m_absoluteURL;
+			}
+
+			if (m_repositoryURL.isEmpty())
+			{
+				return QString("https://" + URLConstants::LIBRARY_BASE) + raw_storage;
+			}
+
+			if(m_repositoryURL.endsWith('/'))
+			{
+				return m_repositoryURL + raw_storage;
+			}
+			else
+			{
+				return m_repositoryURL + QChar('/') + raw_storage;
+			}
+		}();
+		if (raw_storage.contains("${arch}"))
+		{
+			QString cooked_storage = raw_storage;
+			QString cooked_dl = raw_dl;
+			add_download(cooked_storage.replace("${arch}", "32"), cooked_dl.replace("${arch}", "32"));
+			cooked_storage = raw_storage;
+			cooked_dl = raw_dl;
+			add_download(cooked_storage.replace("${arch}", "64"), cooked_dl.replace("${arch}", "64"));
+		}
+		else
+		{
+			add_download(raw_storage, raw_dl);
+		}
+	}
+	return out;
+}
+
 bool Library::isActive() const
 {
 	bool result = true;
@@ -74,7 +193,7 @@ bool Library::isActive() const
 	}
 	if (isNative())
 	{
-		result = result && m_native_classifiers.contains(currentSystem);
+		result = result && m_nativeClassifiers.contains(currentSystem);
 	}
 	return result;
 }
@@ -98,7 +217,7 @@ QString Library::storagePrefix() const
 	return m_storagePrefix;
 }
 
-QString Library::storageSuffix() const
+QString Library::storageSuffix(OpSys system) const
 {
 	// non-native? use only the gradle specifier
 	if (!isNative())
@@ -108,9 +227,9 @@ QString Library::storageSuffix() const
 
 	// otherwise native, override classifiers. Mojang HACK!
 	GradleSpecifier nativeSpec = m_name;
-	if (m_native_classifiers.contains(currentSystem))
+	if (m_nativeClassifiers.contains(system))
 	{
-		nativeSpec.setClassifier(m_native_classifiers[currentSystem]);
+		nativeSpec.setClassifier(m_nativeClassifiers[system]);
 	}
 	else
 	{
@@ -118,13 +237,3 @@ QString Library::storageSuffix() const
 	}
 	return nativeSpec.toPath();
 }
-
-QString Library::storagePath() const
-{
-	return FS::PathCombine(storagePrefix(), storageSuffix());
-}
-
-bool Library::storagePathIsDefault() const
-{
-	return m_storagePrefix.isEmpty();
-}
diff --git a/logic/minecraft/Library.h b/logic/minecraft/Library.h
index 35b5cb99..fdce93f3 100644
--- a/logic/minecraft/Library.h
+++ b/logic/minecraft/Library.h
@@ -1,5 +1,6 @@
 #pragma once
 #include <QString>
+#include <net/NetAction.h>
 #include <QPair>
 #include <QList>
 #include <QStringList>
@@ -12,16 +13,19 @@
 #include "minecraft/OpSys.h"
 #include "GradleSpecifier.h"
 #include "net/URLConstants.h"
+#include "MojangDownloadInfo.h"
+
+#include "multimc_logic_export.h"
 
-struct MojangLibraryDownloadInfo;
 class Library;
 
 typedef std::shared_ptr<Library> LibraryPtr;
 
-class Library
+class MULTIMC_LOGIC_EXPORT Library
 {
 	friend class OneSixVersionFormat;
 	friend class MojangVersionFormat;
+	friend class LibraryTest;
 public:
 	Library()
 	{
@@ -35,13 +39,14 @@ public:
 	{
 		auto newlib = std::make_shared<Library>();
 		newlib->m_name = base->m_name;
-		newlib->m_base_url = base->m_base_url;
+		newlib->m_repositoryURL = base->m_repositoryURL;
 		newlib->m_hint = base->m_hint;
-		newlib->m_absolute_url = base->m_absolute_url;
-		newlib->extract_excludes = base->extract_excludes;
-		newlib->m_native_classifiers = base->m_native_classifiers;
+		newlib->m_absoluteURL = base->m_absoluteURL;
+		newlib->m_extractExcludes = base->m_extractExcludes;
+		newlib->m_nativeClassifiers = base->m_nativeClassifiers;
 		newlib->m_rules = base->m_rules;
 		newlib->m_storagePrefix = base->m_storagePrefix;
+		newlib->m_mojangDownloads = base->m_mojangDownloads;
 		return newlib;
 	}
 
@@ -83,45 +88,27 @@ public: /* methods */
 	/// Returns true if the library is native
 	bool isNative() const
 	{
-		return m_native_classifiers.size() != 0;
+		return m_nativeClassifiers.size() != 0;
 	}
 
 	void setStoragePrefix(QString prefix = QString());
 
-	/// the default storage prefix used by MultiMC
-	static QString defaultStoragePrefix();
-
-	bool storagePathIsDefault() const;
-
-	/// Get the prefix - root of the storage to be used
-	QString storagePrefix() const;
-
-	/// Get the relative path where the library should be saved
-	QString storageSuffix() const;
-
-	/// Get the absolute path where the library should be saved
-	QString storagePath() const;
-
 	/// Set the url base for downloads
-	void setBaseUrl(const QString &base_url)
+	void setRepositoryURL(const QString &base_url)
 	{
-		m_base_url = base_url;
+		m_repositoryURL = base_url;
 	}
 
-	/// List of files this library describes. Required because of platform-specificness of native libs
-	QStringList files() const;
-
-	/// List Shortcut for checking if all the above files exist
-	bool filesExist(const QDir &base) const;
+	void getApplicableFiles(OpSys system, QStringList & jar, QStringList & native, QStringList & native32, QStringList & native64) const;
 
 	void setAbsoluteUrl(const QString &absolute_url)
 	{
-		m_absolute_url = absolute_url;
+		m_absoluteURL = absolute_url;
 	}
 
-	QString absoluteUrl() const
+	void setMojangDownloadInfo(MojangLibraryDownloadInfo::Ptr info)
 	{
-		return m_absolute_url;
+		m_mojangDownloads = info;
 	}
 
 	void setHint(const QString &hint)
@@ -129,11 +116,6 @@ public: /* methods */
 		m_hint = hint;
 	}
 
-	QString hint() const
-	{
-		return m_hint;
-	}
-
 	/// Set the load rules
 	void setRules(QList<std::shared_ptr<Rule>> rules)
 	{
@@ -143,22 +125,33 @@ public: /* methods */
 	/// Returns true if the library should be loaded (or extracted, in case of natives)
 	bool isActive() const;
 
-	/// Get the URL to download the library from
-	QString url() const;
+	// Get a list of downloads for this library
+	QList<NetActionPtr> getDownloads(OpSys system, class HttpMetaCache * cache, QStringList &failedFiles) const;
+
+private: /* methods */
+	/// the default storage prefix used by MultiMC
+	static QString defaultStoragePrefix();
+
+	/// Get the prefix - root of the storage to be used
+	QString storagePrefix() const;
+
+	/// Get the relative path where the library should be saved
+	QString storageSuffix(OpSys system) const;
+
+	QString hint() const
+	{
+		return m_hint;
+	}
 
 protected: /* data */
 	/// the basic gradle dependency specifier.
 	GradleSpecifier m_name;
-	/// where to store the lib locally
-	QString m_storage_path;
-	/// is this lib actually active on the current OS?
-	bool m_is_active = false;
 
 	/// DEPRECATED URL prefix of the maven repo where the file can be downloaded
-	QString m_base_url;
+	QString m_repositoryURL;
 
 	/// DEPRECATED: MultiMC-specific absolute URL. takes precedence over the implicit maven repo URL, if defined
-	QString m_absolute_url;
+	QString m_absoluteURL;
 
 	/**
 	 * MultiMC-specific type hint - modifies how the library is treated
@@ -172,13 +165,13 @@ protected: /* data */
 	QString m_storagePrefix;
 
 	/// true if the library had an extract/excludes section (even empty)
-	bool applyExcludes = false;
+	bool m_hasExcludes = false;
 
 	/// a list of files that shouldn't be extracted from the library
-	QStringList extract_excludes;
+	QStringList m_extractExcludes;
 
 	/// native suffixes per OS
-	QMap<OpSys, QString> m_native_classifiers;
+	QMap<OpSys, QString> m_nativeClassifiers;
 
 	/// true if the library had a rules section (even empty)
 	bool applyRules = false;
@@ -187,5 +180,5 @@ protected: /* data */
 	QList<std::shared_ptr<Rule>> m_rules;
 
 	/// MOJANG: container with Mojang style download info
-	std::shared_ptr<MojangLibraryDownloadInfo> m_mojang_downloads;
+	MojangLibraryDownloadInfo::Ptr m_mojangDownloads;
 };
diff --git a/logic/minecraft/MinecraftProfile.cpp b/logic/minecraft/MinecraftProfile.cpp
index 71ece012..70d0cee4 100644
--- a/logic/minecraft/MinecraftProfile.cpp
+++ b/logic/minecraft/MinecraftProfile.cpp
@@ -14,6 +14,7 @@
  */
 
 #include <QFile>
+#include <QCryptographicHash>
 #include <Version.h>
 #include <QDir>
 #include <QJsonDocument>
@@ -68,9 +69,9 @@ void MinecraftProfile::clear()
 	m_mainClass.clear();
 	m_appletClass.clear();
 	m_libraries.clear();
-	m_nativeLibraries.clear();
 	m_traits.clear();
 	m_jarMods.clear();
+	mojangDownloads.clear();
 	m_problemSeverity = ProblemSeverity::PROBLEM_NONE;
 }
 
@@ -428,6 +429,18 @@ void MinecraftProfile::applyMinecraftAssets(MojangAssetIndexInfo::Ptr assets)
 	}
 }
 
+void MinecraftProfile::applyMojangDownload(const QString &key, MojangDownloadInfo::Ptr download)
+{
+	if(download)
+	{
+		mojangDownloads[key] = download;
+	}
+	else
+	{
+		mojangDownloads.remove(key);
+	}
+}
+
 void MinecraftProfile::applyTraits(const QSet<QString>& traits)
 {
 	this->m_traits.unite(traits);
@@ -466,35 +479,24 @@ static int findLibraryByName(QList<LibraryPtr> haystack, const GradleSpecifier &
 
 void MinecraftProfile::applyLibrary(LibraryPtr library)
 {
-	auto insert = [&](QList<LibraryPtr> & into)
-	{
-		// find the library by name.
-		const int index = findLibraryByName(into, library->rawName());
-		// library not found? just add it.
-		if (index < 0)
-		{
-			into.append(Library::limitedCopy(library));
-			return;
-		}
-		auto existingLibrary = into.at(index);
-		// if we are higher it means we should update
-		if (Version(library->version()) > Version(existingLibrary->version()))
-		{
-			auto libraryCopy = Library::limitedCopy(library);
-			into.replace(index, libraryCopy);
-		}
-	};
 	if(!library->isActive())
 	{
 		return;
 	}
-	if(library->isNative())
+	// find the library by name.
+	const int index = findLibraryByName(m_libraries, library->rawName());
+	// library not found? just add it.
+	if (index < 0)
 	{
-		insert(m_nativeLibraries);
+		m_libraries.append(Library::limitedCopy(library));
+		return;
 	}
-	else
+	auto existingLibrary = m_libraries.at(index);
+	// if we are higher it means we should update
+	if (Version(library->version()) > Version(existingLibrary->version()))
 	{
-		insert(m_libraries);
+		auto libraryCopy = Library::limitedCopy(library);
+		m_libraries.replace(index, libraryCopy);
 	}
 }
 
@@ -571,12 +573,21 @@ const QList<LibraryPtr> & MinecraftProfile::getLibraries() const
 	return m_libraries;
 }
 
-const QList<LibraryPtr> & MinecraftProfile::getNativeLibraries() const
+QString MinecraftProfile::getMainJarUrl() const
 {
-	return m_nativeLibraries;
+	auto iter = mojangDownloads.find("client");
+	if(iter != mojangDownloads.end())
+	{
+		// current
+		return iter.value()->url;
+	}
+	else
+	{
+		// legacy fallback
+		return URLConstants::getLegacyJarUrl(getMinecraftVersion());
+	}
 }
 
-
 void MinecraftProfile::installJarMods(QStringList selectedFiles)
 {
 	m_strategy->installJarMods(selectedFiles);
diff --git a/logic/minecraft/MinecraftProfile.h b/logic/minecraft/MinecraftProfile.h
index ce0ff3cf..ca9288ad 100644
--- a/logic/minecraft/MinecraftProfile.h
+++ b/logic/minecraft/MinecraftProfile.h
@@ -97,6 +97,7 @@ public: /* application of profile variables from patches */
 	void applyJarMods(const QList<JarmodPtr> &jarMods);
 	void applyLibrary(LibraryPtr library);
 	void applyProblemSeverity(ProblemSeverity severity);
+	void applyMojangDownload(const QString & key, MojangDownloadInfo::Ptr download);
 
 public: /* getters for profile variables */
 	QString getMinecraftVersion() const;
@@ -109,7 +110,7 @@ public: /* getters for profile variables */
 	const QStringList & getTweakers() const;
 	const QList<JarmodPtr> & getJarMods() const;
 	const QList<LibraryPtr> & getLibraries() const;
-	const QList<LibraryPtr> & getNativeLibraries() const;
+	QString getMainJarUrl() const;
 	bool hasTrait(const QString & trait) const;
 	ProblemSeverity getProblemSeverity() const;
 
@@ -139,6 +140,9 @@ private: /* data */
 	/// Assets type - "legacy" or a version ID
 	MojangAssetIndexInfo::Ptr m_minecraftAssets;
 
+	// Mojang: list of 'downloads' - client jar, server jar, windows server exe, maybe more.
+	QMap <QString, std::shared_ptr<MojangDownloadInfo>> mojangDownloads;
+
 	/**
 	 * arguments that should be used for launching minecraft
 	 *
@@ -159,9 +163,6 @@ private: /* data */
 	/// the list of libraries
 	QList<LibraryPtr> m_libraries;
 
-	/// the list of native libraries
-	QList<LibraryPtr> m_nativeLibraries;
-
 	/// traits, collected from all the version files (version files can only add)
 	QSet<QString> m_traits;
 
diff --git a/logic/minecraft/MinecraftVersion.cpp b/logic/minecraft/MinecraftVersion.cpp
index a3855481..3167fc4a 100644
--- a/logic/minecraft/MinecraftVersion.cpp
+++ b/logic/minecraft/MinecraftVersion.cpp
@@ -72,10 +72,12 @@ void MinecraftVersion::applyFileTo(MinecraftProfile *profile)
 
 QString MinecraftVersion::getUrl() const
 {
+	// legacy fallback
 	if(m_versionFileURL.isEmpty())
 	{
 		return QString("http://") + URLConstants::AWS_DOWNLOAD_VERSIONS + m_descriptor + "/" + m_descriptor + ".json";
 	}
+	// current
 	return m_versionFileURL;
 }
 
diff --git a/logic/minecraft/MinecraftVersionList.cpp b/logic/minecraft/MinecraftVersionList.cpp
index 62c588d1..bd679c73 100644
--- a/logic/minecraft/MinecraftVersionList.cpp
+++ b/logic/minecraft/MinecraftVersionList.cpp
@@ -470,8 +470,7 @@ void MCVListVersionUpdateTask::executeTask()
 	specificVersionDownloadJob.reset(job);
 	connect(specificVersionDownloadJob.get(), SIGNAL(succeeded()), SLOT(json_downloaded()));
 	connect(specificVersionDownloadJob.get(), SIGNAL(failed(QString)), SIGNAL(failed(QString)));
-	connect(specificVersionDownloadJob.get(), SIGNAL(progress(qint64, qint64)),
-			SIGNAL(progress(qint64, qint64)));
+	connect(specificVersionDownloadJob.get(), SIGNAL(progress(qint64, qint64)), SIGNAL(progress(qint64, qint64)));
 	specificVersionDownloadJob->start();
 }
 
diff --git a/logic/minecraft/MojangDownloadInfo.h b/logic/minecraft/MojangDownloadInfo.h
index d8cd2e6d..1f3306e0 100644
--- a/logic/minecraft/MojangDownloadInfo.h
+++ b/logic/minecraft/MojangDownloadInfo.h
@@ -1,5 +1,6 @@
 #pragma once
 #include <QString>
+#include <QMap>
 #include <memory>
 
 struct MojangDownloadInfo
@@ -22,6 +23,9 @@ struct MojangDownloadInfo
 
 struct MojangLibraryDownloadInfo
 {
+	MojangLibraryDownloadInfo(MojangDownloadInfo::Ptr artifact): artifact(artifact) {};
+	MojangLibraryDownloadInfo() {};
+
 	// types
 	typedef std::shared_ptr<MojangLibraryDownloadInfo> Ptr;
 
diff --git a/logic/minecraft/MojangVersionFormat.cpp b/logic/minecraft/MojangVersionFormat.cpp
index 41723493..34129c9e 100644
--- a/logic/minecraft/MojangVersionFormat.cpp
+++ b/logic/minecraft/MojangVersionFormat.cpp
@@ -8,7 +8,7 @@
 using namespace Json;
 #include "ParseUtils.h"
 
-static const int CURRENT_MINIMUM_LAUNCHER_VERSION = 14;
+static const int CURRENT_MINIMUM_LAUNCHER_VERSION = 18;
 
 static MojangAssetIndexInfo::Ptr assetIndexFromJson (const QJsonObject &obj);
 static MojangDownloadInfo::Ptr downloadInfoFromJson (const QJsonObject &obj);
@@ -130,7 +130,7 @@ QJsonObject assetIndexToJson(MojangAssetIndexInfo::Ptr info)
 
 void MojangVersionFormat::readVersionProperties(const QJsonObject &in, VersionFile *out)
 {
-	Bits::readString(in, "id", out->id);
+	Bits::readString(in, "id", out->minecraftVersion);
 	Bits::readString(in, "mainClass", out->mainClass);
 	Bits::readString(in, "minecraftArguments", out->minecraftArguments);
 	if(out->minecraftArguments.isEmpty())
@@ -212,7 +212,7 @@ VersionFilePtr MojangVersionFormat::versionFileFromJson(const QJsonDocument &doc
 
 	out->name = "Minecraft";
 	out->fileId = "net.minecraft";
-	out->version = out->id;
+	out->version = out->minecraftVersion;
 	out->filename = filename;
 
 
@@ -231,7 +231,7 @@ VersionFilePtr MojangVersionFormat::versionFileFromJson(const QJsonDocument &doc
 
 void MojangVersionFormat::writeVersionProperties(const VersionFile* in, QJsonObject& out)
 {
-	writeString(out, "id", in->id);
+	writeString(out, "id", in->minecraftVersion);
 	writeString(out, "mainClass", in->mainClass);
 	writeString(out, "minecraftArguments", in->minecraftArguments);
 	writeString(out, "type", in->type);
@@ -294,14 +294,14 @@ LibraryPtr MojangVersionFormat::libraryFromJson(const QJsonObject &libObj, const
 	}
 	out->m_name = libObj.value("name").toString();
 
-	Bits::readString(libObj, "url", out->m_base_url);
+	Bits::readString(libObj, "url", out->m_repositoryURL);
 	if (libObj.contains("extract"))
 	{
-		out->applyExcludes = true;
+		out->m_hasExcludes = true;
 		auto extractObj = requireObject(libObj.value("extract"));
 		for (auto excludeVal : requireArray(extractObj.value("exclude")))
 		{
-			out->extract_excludes.append(requireString(excludeVal));
+			out->m_extractExcludes.append(requireString(excludeVal));
 		}
 	}
 	if (libObj.contains("natives"))
@@ -316,7 +316,7 @@ LibraryPtr MojangVersionFormat::libraryFromJson(const QJsonObject &libObj, const
 			OpSys opSys = OpSys_fromString(it.key());
 			if (opSys != Os_Other)
 			{
-				out->m_native_classifiers[opSys] = it.value().toString();
+				out->m_nativeClassifiers[opSys] = it.value().toString();
 			}
 		}
 	}
@@ -327,7 +327,7 @@ LibraryPtr MojangVersionFormat::libraryFromJson(const QJsonObject &libObj, const
 	}
 	if (libObj.contains("downloads"))
 	{
-		out->m_mojang_downloads = libDownloadInfoFromJson(libObj);
+		out->m_mojangDownloads = libDownloadInfoFromJson(libObj);
 	}
 	return out;
 }
@@ -336,27 +336,25 @@ QJsonObject MojangVersionFormat::libraryToJson(Library *library)
 {
 	QJsonObject libRoot;
 	libRoot.insert("name", (QString)library->m_name);
-	if (library->m_base_url != "http://" + URLConstants::AWS_DOWNLOAD_LIBRARIES &&
-		library->m_base_url != "https://" + URLConstants::AWS_DOWNLOAD_LIBRARIES &&
-		library->m_base_url != "https://" + URLConstants::LIBRARY_BASE && !library->m_base_url.isEmpty())
+	if (!library->m_repositoryURL.isEmpty())
 	{
-		libRoot.insert("url", library->m_base_url);
+		libRoot.insert("url", library->m_repositoryURL);
 	}
 	if (library->isNative())
 	{
 		QJsonObject nativeList;
-		auto iter = library->m_native_classifiers.begin();
-		while (iter != library->m_native_classifiers.end())
+		auto iter = library->m_nativeClassifiers.begin();
+		while (iter != library->m_nativeClassifiers.end())
 		{
 			nativeList.insert(OpSys_toString(iter.key()), iter.value());
 			iter++;
 		}
 		libRoot.insert("natives", nativeList);
-		if (library->extract_excludes.size())
+		if (library->m_extractExcludes.size())
 		{
 			QJsonArray excludes;
 			QJsonObject extract;
-			for (auto exclude : library->extract_excludes)
+			for (auto exclude : library->m_extractExcludes)
 			{
 				excludes.append(exclude);
 			}
@@ -374,9 +372,9 @@ QJsonObject MojangVersionFormat::libraryToJson(Library *library)
 		}
 		libRoot.insert("rules", allRules);
 	}
-	if(library->m_mojang_downloads)
+	if(library->m_mojangDownloads)
 	{
-		auto downloadsObj = libDownloadInfoToJson(library->m_mojang_downloads);
+		auto downloadsObj = libDownloadInfoToJson(library->m_mojangDownloads);
 		libRoot.insert("downloads", downloadsObj);
 	}
 	return libRoot;
diff --git a/logic/minecraft/VersionFile.cpp b/logic/minecraft/VersionFile.cpp
index 451c3c8b..573c4cb4 100644
--- a/logic/minecraft/VersionFile.cpp
+++ b/logic/minecraft/VersionFile.cpp
@@ -25,14 +25,14 @@ bool VersionFile::hasJarMods()
 void VersionFile::applyTo(MinecraftProfile *profile)
 {
 	auto theirVersion = profile->getMinecraftVersion();
-	if (!theirVersion.isNull() && !mcVersion.isNull())
+	if (!theirVersion.isNull() && !dependsOnMinecraftVersion.isNull())
 	{
-		if (QRegExp(mcVersion, Qt::CaseInsensitive, QRegExp::Wildcard).indexIn(theirVersion) == -1)
+		if (QRegExp(dependsOnMinecraftVersion, Qt::CaseInsensitive, QRegExp::Wildcard).indexIn(theirVersion) == -1)
 		{
-			throw MinecraftVersionMismatch(fileId, mcVersion, theirVersion);
+			throw MinecraftVersionMismatch(fileId, dependsOnMinecraftVersion, theirVersion);
 		}
 	}
-	profile->applyMinecraftVersion(id);
+	profile->applyMinecraftVersion(minecraftVersion);
 	profile->applyMainClass(mainClass);
 	profile->applyAppletClass(appletClass);
 	profile->applyMinecraftArguments(minecraftArguments);
@@ -51,4 +51,10 @@ void VersionFile::applyTo(MinecraftProfile *profile)
 		profile->applyLibrary(library);
 	}
 	profile->applyProblemSeverity(getProblemSeverity());
+	auto iter = mojangDownloads.begin();
+	while(iter != mojangDownloads.end())
+	{
+		profile->applyMojangDownload(iter.key(), iter.value());
+		iter++;
+	}
 }
diff --git a/logic/minecraft/VersionFile.h b/logic/minecraft/VersionFile.h
index 7627cc96..1b692f0f 100644
--- a/logic/minecraft/VersionFile.h
+++ b/logic/minecraft/VersionFile.h
@@ -143,13 +143,13 @@ public: /* data */
 	QString version;
 
 	/// MultiMC: dependency on a Minecraft version
-	QString mcVersion;
+	QString dependsOnMinecraftVersion;
 
 	/// Mojang: used to version the Mojang version format
 	int minimumLauncherVersion = -1;
 
 	/// Mojang: version of Minecraft this is
-	QString id;
+	QString minecraftVersion;
 
 	/// Mojang: class to launch Minecraft with
 	QString mainClass;
diff --git a/logic/minecraft/forge/ForgeInstaller.cpp b/logic/minecraft/forge/ForgeInstaller.cpp
index 7957de0e..155a2cac 100644
--- a/logic/minecraft/forge/ForgeInstaller.cpp
+++ b/logic/minecraft/forge/ForgeInstaller.cpp
@@ -126,8 +126,8 @@ void ForgeInstaller::prepare(const QString &filename, const QString &universalUr
 		QCryptographicHash md5sum(QCryptographicHash::Md5);
 		md5sum.addData(data);
 
-		cacheentry->stale = false;
-		cacheentry->md5sum = md5sum.result().toHex().constData();
+		cacheentry->setStale(false);
+		cacheentry->setMD5Sum(md5sum.result().toHex().constData());
 		ENV.metacache()->updateEntry(cacheentry);
 	}
 	file.close();
@@ -264,8 +264,8 @@ bool ForgeInstaller::add(OneSixInstance *to)
 	m_forge_json->name = "Forge";
 	m_forge_json->fileId = id();
 	m_forge_json->version = m_forgeVersionString;
-	m_forge_json->mcVersion = to->intendedVersionId();
-	m_forge_json->id.clear();
+	m_forge_json->dependsOnMinecraftVersion = to->intendedVersionId();
+	m_forge_json->minecraftVersion.clear();
 	m_forge_json->order = 5;
 
 	QSaveFile file(filename(to->instanceRoot()));
@@ -378,16 +378,16 @@ protected:
 		 * This fixes some problems with bad files acquired because of unhandled HTTP redirects
 		 * in old versions of MultiMC.
 		 */
-		if (!entry->stale)
+		if (!entry->isStale())
 		{
 			QFileInfo localFile(entry->getFullPath());
 			if (localFile.size() <= 0x4000)
 			{
-				entry->stale = true;
+				entry->setStale(true);
 			}
 		}
 
-		if (entry->stale)
+		if (entry->isStale())
 		{
 			NetJob *fjob = new NetJob("Forge download");
 			fjob->addNetAction(CacheDownload::make(forgeVersion->url(), entry));
diff --git a/logic/minecraft/forge/ForgeMirror.h b/logic/minecraft/forge/ForgeMirror.h
deleted file mode 100644
index 2518dffe..00000000
--- a/logic/minecraft/forge/ForgeMirror.h
+++ /dev/null
@@ -1,10 +0,0 @@
-#pragma once
-#include <QString>
-
-struct ForgeMirror
-{
-	QString name;
-	QString logo_url;
-	QString website_url;
-	QString mirror_url;
-};
\ No newline at end of file
diff --git a/logic/minecraft/forge/ForgeMirrors.cpp b/logic/minecraft/forge/ForgeMirrors.cpp
deleted file mode 100644
index a2fc2c62..00000000
--- a/logic/minecraft/forge/ForgeMirrors.cpp
+++ /dev/null
@@ -1,118 +0,0 @@
-#include "Env.h"
-#include "ForgeMirrors.h"
-#include <QDebug>
-#include <algorithm>
-#include <random>
-
-ForgeMirrors::ForgeMirrors(QList<ForgeXzDownloadPtr> &libs, NetJobPtr parent_job,
-						   QString mirrorlist)
-{
-	m_libs = libs;
-	m_parent_job = parent_job;
-	m_url = QUrl(mirrorlist);
-	m_status = Job_NotStarted;
-}
-
-void ForgeMirrors::start()
-{
-	qDebug() << "Downloading " << m_url.toString();
-	QNetworkRequest request(m_url);
-	request.setHeader(QNetworkRequest::UserAgentHeader, "MultiMC/5.0 (Uncached)");
-	auto worker = ENV.qnam();
-	QNetworkReply *rep = worker->get(request);
-
-	m_reply.reset(rep);
-	connect(rep, SIGNAL(downloadProgress(qint64, qint64)),
-			SLOT(downloadProgress(qint64, qint64)));
-	connect(rep, SIGNAL(finished()), SLOT(downloadFinished()));
-	connect(rep, SIGNAL(error(QNetworkReply::NetworkError)),
-			SLOT(downloadError(QNetworkReply::NetworkError)));
-	connect(rep, SIGNAL(readyRead()), SLOT(downloadReadyRead()));
-}
-
-void ForgeMirrors::downloadError(QNetworkReply::NetworkError error)
-{
-	// error happened during download.
-	qCritical() << "Error getting URL:" << m_url.toString().toLocal8Bit()
-				 << "Network error: " << error;
-	m_status = Job_Failed;
-}
-
-void ForgeMirrors::downloadFinished()
-{
-	// if the download succeeded
-	if (m_status != Job_Failed)
-	{
-		// nothing went wrong... ?
-		parseMirrorList();
-		return;
-	}
-	// else the download failed, we use a fixed list
-	else
-	{
-		m_status = Job_Finished;
-		m_reply.reset();
-		deferToFixedList();
-		return;
-	}
-}
-
-void ForgeMirrors::deferToFixedList()
-{
-	m_mirrors.clear();
-	m_mirrors.append(
-		{"Minecraft Forge",				  "http://files.minecraftforge.net/forge_logo.png",
-		 "http://files.minecraftforge.net/", "http://files.minecraftforge.net/maven/"});
-	m_mirrors.append({"Creeper Host",
-					  "http://files.minecraftforge.net/forge_logo.png",
-					  "https://www.creeperhost.net/link.php?id=1",
-					  "http://new.creeperrepo.net/forge/maven/"});
-	injectDownloads();
-	emit succeeded(m_index_within_job);
-}
-
-void ForgeMirrors::parseMirrorList()
-{
-	m_status = Job_Finished;
-	auto data = m_reply->readAll();
-	m_reply.reset();
-	auto dataLines = data.split('\n');
-	for(auto line: dataLines)
-	{
-		auto elements = line.split('!');
-		if (elements.size() == 4)
-		{
-			m_mirrors.append({elements[0],elements[1],elements[2],elements[3]});
-		}
-	}
-	if(!m_mirrors.size())
-		deferToFixedList();
-	injectDownloads();
-	emit succeeded(m_index_within_job);
-}
-
-void ForgeMirrors::injectDownloads()
-{
-	// shuffle the mirrors randomly
-	std::random_device rd;
-	std::mt19937 rng(rd());
-	std::shuffle(m_mirrors.begin(), m_mirrors.end(), rng);
-
-	// tell parent to download the libs
-	for(auto lib: m_libs)
-	{
-		lib->setMirrors(m_mirrors);
-		m_parent_job->addNetAction(lib);
-	}
-}
-
-void ForgeMirrors::downloadProgress(qint64 bytesReceived, qint64 bytesTotal)
-{
-	m_total_progress = bytesTotal;
-	m_progress = bytesReceived;
-	emit netActionProgress(m_index_within_job, bytesReceived, bytesTotal);
-}
-
-void ForgeMirrors::downloadReadyRead()
-{
-}
diff --git a/logic/minecraft/forge/ForgeMirrors.h b/logic/minecraft/forge/ForgeMirrors.h
deleted file mode 100644
index 0312829b..00000000
--- a/logic/minecraft/forge/ForgeMirrors.h
+++ /dev/null
@@ -1,61 +0,0 @@
-/* Copyright 2013-2015 MultiMC Contributors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#pragma once
-
-#include "ForgeXzDownload.h"
-
-#include "net/NetAction.h"
-#include "net/HttpMetaCache.h"
-#include "net/NetJob.h"
-
-#include <QFile>
-#include <QTemporaryFile>
-
-typedef std::shared_ptr<class ForgeMirrors> ForgeMirrorsPtr;
-
-class ForgeMirrors : public NetAction
-{
-	Q_OBJECT
-public:
-	QList<ForgeXzDownloadPtr> m_libs;
-	NetJobPtr m_parent_job;
-	QList<ForgeMirror> m_mirrors;
-
-public:
-	explicit ForgeMirrors(QList<ForgeXzDownloadPtr> &libs, NetJobPtr parent_job,
-						  QString mirrorlist);
-	static ForgeMirrorsPtr make(QList<ForgeXzDownloadPtr> &libs, NetJobPtr parent_job,
-								QString mirrorlist)
-	{
-		return ForgeMirrorsPtr(new ForgeMirrors(libs, parent_job, mirrorlist));
-	}
-	virtual ~ForgeMirrors(){};
-protected
-slots:
-	virtual void downloadProgress(qint64 bytesReceived, qint64 bytesTotal);
-	virtual void downloadError(QNetworkReply::NetworkError error);
-	virtual void downloadFinished();
-	virtual void downloadReadyRead();
-
-private:
-	void parseMirrorList();
-	void deferToFixedList();
-	void injectDownloads();
-
-public
-slots:
-	virtual void start();
-};
diff --git a/logic/minecraft/forge/ForgeVersionList.cpp b/logic/minecraft/forge/ForgeVersionList.cpp
index 9b418310..907672f2 100644
--- a/logic/minecraft/forge/ForgeVersionList.cpp
+++ b/logic/minecraft/forge/ForgeVersionList.cpp
@@ -128,8 +128,8 @@ void ForgeListLoadTask::executeTask()
 	auto gradleForgeListEntry = ENV.metacache()->resolveEntry("minecraftforge", "json");
 
 	// verify by poking the server.
-	forgeListEntry->stale = true;
-	gradleForgeListEntry->stale = true;
+	forgeListEntry->setStale(true);
+	gradleForgeListEntry->setStale(true);
 
 	job->addNetAction(listDownload = CacheDownload::make(QUrl(URLConstants::FORGE_LEGACY_URL),
 														 forgeListEntry));
diff --git a/logic/minecraft/forge/ForgeXzDownload.cpp b/logic/minecraft/forge/ForgeXzDownload.cpp
index 6009e31e..2a47bb26 100644
--- a/logic/minecraft/forge/ForgeXzDownload.cpp
+++ b/logic/minecraft/forge/ForgeXzDownload.cpp
@@ -30,19 +30,13 @@ ForgeXzDownload::ForgeXzDownload(QString relative_path, MetaEntryPtr entry) : Ne
 	m_pack200_xz_file.setFileTemplate("./dl_temp.XXXXXX");
 	m_status = Job_NotStarted;
 	m_url_path = relative_path;
-}
-
-void ForgeXzDownload::setMirrors(QList<ForgeMirror> &mirrors)
-{
-	m_mirror_index = 0;
-	m_mirrors = mirrors;
-	updateUrl();
+	m_url = "http://files.minecraftforge.net/maven/" + m_url_path + ".pack.xz";
 }
 
 void ForgeXzDownload::start()
 {
 	m_status = Job_InProgress;
-	if (!m_entry->stale)
+	if (!m_entry->isStale())
 	{
 		m_status = Job_Finished;
 		emit succeeded(m_index_within_job);
@@ -55,16 +49,10 @@ void ForgeXzDownload::start()
 		emit failed(m_index_within_job);
 		return;
 	}
-	if (m_mirrors.empty())
-	{
-		m_status = Job_Failed;
-		emit failed(m_index_within_job);
-		return;
-	}
 
 	qDebug() << "Downloading " << m_url.toString();
 	QNetworkRequest request(m_url);
-	request.setRawHeader(QString("If-None-Match").toLatin1(), m_entry->etag.toLatin1());
+	request.setRawHeader(QString("If-None-Match").toLatin1(), m_entry->getETag().toLatin1());
 	request.setHeader(QNetworkRequest::UserAgentHeader, "MultiMC/5.0 (Cached)");
 
 	auto worker = ENV.qnam();
@@ -96,44 +84,11 @@ void ForgeXzDownload::downloadError(QNetworkReply::NetworkError error)
 void ForgeXzDownload::failAndTryNextMirror()
 {
 	m_status = Job_Failed;
-	int next = m_mirror_index + 1;
-	if(m_mirrors.size() == next)
-		m_mirror_index = 0;
-	else
-		m_mirror_index = next;
-
-	updateUrl();
 	emit failed(m_index_within_job);
 }
 
-void ForgeXzDownload::updateUrl()
-{
-	qDebug() << "Updating URL for " << m_url_path;
-	for (auto possible : m_mirrors)
-	{
-		qDebug() << "Possible: " << possible.name << " : " << possible.mirror_url;
-	}
-	QString aggregate = m_mirrors[m_mirror_index].mirror_url + m_url_path + ".pack.xz";
-	m_url = QUrl(aggregate);
-}
-
 void ForgeXzDownload::downloadFinished()
 {
-	//TEST: defer to other possible mirrors (autofail the first one)
-	/*
-	qDebug() <<"dl " << index_within_job << " mirror " << m_mirror_index;
-	if( m_mirror_index == 0)
-	{
-		qDebug() <<"dl " << index_within_job << " AUTOFAIL";
-		m_status = Job_Failed;
-		m_pack200_xz_file.close();
-		m_pack200_xz_file.remove();
-		m_reply.reset();
-		failAndTryNextMirror();
-		return;
-	}
-	*/
-
 	// if the download succeeded
 	if (m_status != Job_Failed)
 	{
@@ -372,16 +327,14 @@ void ForgeXzDownload::decompressAndInstall()
 		failAndTryNextMirror();
 		return;
 	}
-	m_entry->md5sum = QCryptographicHash::hash(jar_file.readAll(), QCryptographicHash::Md5)
-						  .toHex()
-						  .constData();
+	auto hash = QCryptographicHash::hash(jar_file.readAll(), QCryptographicHash::Md5);
+	m_entry->setMD5Sum(hash.toHex().constData());
 	jar_file.close();
 
 	QFileInfo output_file_info(m_target_path);
-	m_entry->etag = m_reply->rawHeader("ETag").constData();
-	m_entry->local_changed_timestamp =
-		output_file_info.lastModified().toUTC().toMSecsSinceEpoch();
-	m_entry->stale = false;
+	m_entry->setETag(m_reply->rawHeader("ETag").constData());
+	m_entry->setLocalChangedTimestamp(output_file_info.lastModified().toUTC().toMSecsSinceEpoch());
+	m_entry->setStale(false);
 	ENV.metacache()->updateEntry(m_entry);
 
 	m_reply.reset();
diff --git a/logic/minecraft/forge/ForgeXzDownload.h b/logic/minecraft/forge/ForgeXzDownload.h
index 45722812..67524405 100644
--- a/logic/minecraft/forge/ForgeXzDownload.h
+++ b/logic/minecraft/forge/ForgeXzDownload.h
@@ -19,7 +19,6 @@
 #include "net/HttpMetaCache.h"
 #include <QFile>
 #include <QTemporaryFile>
-#include "ForgeMirror.h"
 
 typedef std::shared_ptr<class ForgeXzDownload> ForgeXzDownloadPtr;
 
@@ -32,10 +31,6 @@ public:
 	QString m_target_path;
 	/// this is the output file, if any
 	QTemporaryFile m_pack200_xz_file;
-	/// mirror index (NOT OPTICS, I SWEAR)
-	int m_mirror_index = 0;
-	/// list of mirrors to use. Mirror has the url base
-	QList<ForgeMirror> m_mirrors;
 	/// path relative to the mirror base
 	QString m_url_path;
 
@@ -46,7 +41,6 @@ public:
 		return ForgeXzDownloadPtr(new ForgeXzDownload(relative_path, entry));
 	}
 	virtual ~ForgeXzDownload(){};
-	void setMirrors(QList<ForgeMirror> & mirrors);
 
 protected
 slots:
@@ -62,5 +56,4 @@ slots:
 private:
 	void decompressAndInstall();
 	void failAndTryNextMirror();
-	void updateUrl();
 };
diff --git a/logic/minecraft/ftb/FTBProfileStrategy.cpp b/logic/minecraft/ftb/FTBProfileStrategy.cpp
index d43fbf6e..f5faacae 100644
--- a/logic/minecraft/ftb/FTBProfileStrategy.cpp
+++ b/logic/minecraft/ftb/FTBProfileStrategy.cpp
@@ -59,7 +59,7 @@ void FTBProfileStrategy::loadDefaultBuiltinPatches()
 			auto file = ProfileUtils::parseJsonFile(QFileInfo(mcJson), false);
 
 			// adapt the loaded file - the FTB patch file format is different than ours.
-			file->id.clear();
+			file->minecraftVersion.clear();
 			for(auto addLib: file->libraries)
 			{
 				addLib->setHint("local");
diff --git a/logic/minecraft/legacy/LegacyUpdate.cpp b/logic/minecraft/legacy/LegacyUpdate.cpp
index af787f8c..2d7e8dd2 100644
--- a/logic/minecraft/legacy/LegacyUpdate.cpp
+++ b/logic/minecraft/legacy/LegacyUpdate.cpp
@@ -367,14 +367,12 @@ void LegacyUpdate::jarStart()
 	setStatus(tr("Downloading new minecraft.jar ..."));
 
 	QString version_id = inst->intendedVersionId();
-	QString localPath = version_id + "/" + version_id + ".jar";
-	QString urlstr = "http://" + URLConstants::AWS_DOWNLOAD_VERSIONS + localPath;
 
 	auto dljob = new NetJob("Minecraft.jar for version " + version_id);
 
 	auto metacache = ENV.metacache();
-	auto entry = metacache->resolveEntry("versions", localPath);
-	dljob->addNetAction(CacheDownload::make(QUrl(urlstr), entry));
+	auto entry = metacache->resolveEntry("versions", URLConstants::getJarPath(version_id));
+	dljob->addNetAction(CacheDownload::make(QUrl(URLConstants::getLegacyJarUrl(version_id)), entry));
 	connect(dljob, SIGNAL(succeeded()), SLOT(jarFinished()));
 	connect(dljob, SIGNAL(failed(QString)), SLOT(jarFailed(QString)));
 	connect(dljob, SIGNAL(progress(qint64, qint64)), SIGNAL(progress(qint64, qint64)));
diff --git a/logic/minecraft/liteloader/LiteLoaderVersionList.cpp b/logic/minecraft/liteloader/LiteLoaderVersionList.cpp
index 42698ccc..b0c9736a 100644
--- a/logic/minecraft/liteloader/LiteLoaderVersionList.cpp
+++ b/logic/minecraft/liteloader/LiteLoaderVersionList.cpp
@@ -144,7 +144,7 @@ void LLListLoadTask::executeTask()
 	auto liteloaderEntry = ENV.metacache()->resolveEntry("liteloader", "versions.json");
 
 	// verify by poking the server.
-	liteloaderEntry->stale = true;
+	liteloaderEntry->setStale(true);
 
 	job->addNetAction(listDownload = CacheDownload::make(QUrl(URLConstants::LITELOADER_URL),
 														 liteloaderEntry));
@@ -251,7 +251,7 @@ void LLListLoadTask::listDownloaded()
 					// hack to make liteloader 1.7.10_00 work
 					if(lib->rawName() == GradleSpecifier("org.ow2.asm:asm-all:5.0.3"))
 					{
-						lib->setBaseUrl("http://repo.maven.apache.org/maven2/");
+						lib->setRepositoryURL("http://repo.maven.apache.org/maven2/");
 					}
 					version->libraries.append(lib);
 				}
diff --git a/logic/minecraft/onesix/OneSixInstance.cpp b/logic/minecraft/onesix/OneSixInstance.cpp
index 328c3b38..8d46eefc 100644
--- a/logic/minecraft/onesix/OneSixInstance.cpp
+++ b/logic/minecraft/onesix/OneSixInstance.cpp
@@ -180,24 +180,6 @@ QString OneSixInstance::createLaunchScript(AuthSessionPtr session)
 		launchScript += "jarmod " + jarmod->originalName + " (" + jarmod->name + ")\n";
 	}
 
-	// libraries and class path.
-	{
-		auto libs = m_profile->getLibraries();
-		for (auto lib : libs)
-		{
-			launchScript += "cp " + QFileInfo(lib->storagePath()).absoluteFilePath() + "\n";
-		}
-		auto jarMods = getJarMods();
-		if (!jarMods.isEmpty())
-		{
-			launchScript += "cp " + QDir(instanceRoot()).absoluteFilePath("minecraft.jar") + "\n";
-		}
-		else
-		{
-			QString relpath = m_profile->getMinecraftVersion() + "/" + m_profile->getMinecraftVersion() + ".jar";
-			launchScript += "cp " + versionsPath().absoluteFilePath(relpath) + "\n";
-		}
-	}
 	auto mainClass = m_profile->getMainClass();
 	if (!mainClass.isEmpty())
 	{
@@ -234,15 +216,43 @@ QString OneSixInstance::createLaunchScript(AuthSessionPtr session)
 		launchScript += "sessionId " + session->session + "\n";
 	}
 
-	// native libraries (mostly LWJGL)
+	// libraries and class path.
 	{
-		QDir natives_dir(FS::PathCombine(instanceRoot(), "natives/"));
-		for (auto native : m_profile->getNativeLibraries())
+		auto libs = m_profile->getLibraries();
+
+		QStringList jar, native, native32, native64;
+		for (auto lib : libs)
 		{
-			QFileInfo finfo(native->storagePath());
-			launchScript += "ext " + finfo.absoluteFilePath() + "\n";
+			lib->getApplicableFiles(currentSystem, jar, native, native32, native64);
 		}
+		for(auto file: jar)
+		{
+			launchScript += "cp " + file + "\n";
+		}
+		for(auto file: native)
+		{
+			launchScript += "ext " + file + "\n";
+		}
+		for(auto file: native32)
+		{
+			launchScript += "ext32 " + file + "\n";
+		}
+		for(auto file: native64)
+		{
+			launchScript += "ext64 " + file + "\n";
+		}
+		QDir natives_dir(FS::PathCombine(instanceRoot(), "natives/"));
 		launchScript += "natives " + natives_dir.absolutePath() + "\n";
+		auto jarMods = getJarMods();
+		if (!jarMods.isEmpty())
+		{
+			launchScript += "cp " + QDir(instanceRoot()).absoluteFilePath("minecraft.jar") + "\n";
+		}
+		else
+		{
+			QString relpath = m_profile->getMinecraftVersion() + "/" + m_profile->getMinecraftVersion() + ".jar";
+			launchScript += "cp " + versionsPath().absoluteFilePath(relpath) + "\n";
+		}
 	}
 
 	// traits. including legacyLaunch and others ;)
diff --git a/logic/minecraft/onesix/OneSixProfileStrategy.cpp b/logic/minecraft/onesix/OneSixProfileStrategy.cpp
index aaaa9d97..af42286d 100644
--- a/logic/minecraft/onesix/OneSixProfileStrategy.cpp
+++ b/logic/minecraft/onesix/OneSixProfileStrategy.cpp
@@ -54,7 +54,7 @@ void OneSixProfileStrategy::upgradeDeprecatedFiles()
 		auto file = ProfileUtils::parseJsonFile(QFileInfo(sourceFile), false);
 		ProfileUtils::removeLwjglFromPatch(file);
 		file->fileId = "net.minecraft";
-		file->version = file->id;
+		file->version = file->minecraftVersion;
 		file->name = "Minecraft";
 		auto data = OneSixVersionFormat::versionFileToJson(file, false).toJson();
 		QSaveFile newPatchFile(mcJson);
diff --git a/logic/minecraft/onesix/OneSixUpdate.cpp b/logic/minecraft/onesix/OneSixUpdate.cpp
index 10d1e294..1c2cd196 100644
--- a/logic/minecraft/onesix/OneSixUpdate.cpp
+++ b/logic/minecraft/onesix/OneSixUpdate.cpp
@@ -14,6 +14,7 @@
  */
 
 #include "Env.h"
+#include <minecraft/forge/ForgeXzDownload.h>
 #include "OneSixUpdate.h"
 #include "OneSixInstance.h"
 
@@ -29,7 +30,6 @@
 #include "minecraft/MinecraftVersionList.h"
 #include "minecraft/MinecraftProfile.h"
 #include "minecraft/Library.h"
-#include "minecraft/forge/ForgeMirrors.h"
 #include "net/URLConstants.h"
 #include "minecraft/AssetsUtils.h"
 #include "Exception.h"
@@ -95,7 +95,7 @@ void OneSixUpdate::assetIndexStart()
 
 	auto metacache = ENV.metacache();
 	auto entry = metacache->resolveEntry("asset_indexes", localPath);
-	entry->stale = true;
+	entry->setStale(true);
 	job->addNetAction(CacheDownload::make(indexUrl, entry));
 	jarlibDownloadJob.reset(job);
 
@@ -174,88 +174,41 @@ void OneSixUpdate::jarlibStart()
 	{
 		QString version_id = profile->getMinecraftVersion();
 		QString localPath = version_id + "/" + version_id + ".jar";
-		QString urlstr = "http://" + URLConstants::AWS_DOWNLOAD_VERSIONS + localPath;
+		QString urlstr = profile->getMainJarUrl();
 
 		auto job = new NetJob(tr("Libraries for instance %1").arg(inst->name()));
 
 		auto metacache = ENV.metacache();
 		auto entry = metacache->resolveEntry("versions", localPath);
 		job->addNetAction(CacheDownload::make(QUrl(urlstr), entry));
-		jarHashOnEntry = entry->md5sum;
-
 		jarlibDownloadJob.reset(job);
 	}
 
-	auto libs = profile->getNativeLibraries();
-	libs.append(profile->getLibraries());
+	auto libs = profile->getLibraries();
 
 	auto metacache = ENV.metacache();
-	QList<ForgeXzDownloadPtr> ForgeLibs;
 	QList<LibraryPtr> brokenLocalLibs;
 
+	QStringList failedFiles;
 	for (auto lib : libs)
 	{
-		if (lib->hint() == "local")
+		auto dls = lib->getDownloads(currentSystem, metacache.get(), failedFiles);
+		for(auto dl : dls)
 		{
-			if (!lib->filesExist(m_inst->librariesPath()))
-				brokenLocalLibs.append(lib);
-			continue;
-		}
-
-		QString raw_storage = lib->storageSuffix();
-		QString raw_dl = lib->url();
-
-		auto f = [&](QString storage, QString dl)
-		{
-			auto entry = metacache->resolveEntry("libraries", storage);
-			if (entry->stale)
-			{
-				if (lib->hint() == "forge-pack-xz")
-				{
-					ForgeLibs.append(ForgeXzDownload::make(storage, entry));
-				}
-				else
-				{
-					jarlibDownloadJob->addNetAction(CacheDownload::make(dl, entry));
-				}
-			}
-		};
-		if (raw_storage.contains("${arch}"))
-		{
-			QString cooked_storage = raw_storage;
-			QString cooked_dl = raw_dl;
-			f(cooked_storage.replace("${arch}", "32"), cooked_dl.replace("${arch}", "32"));
-			cooked_storage = raw_storage;
-			cooked_dl = raw_dl;
-			f(cooked_storage.replace("${arch}", "64"), cooked_dl.replace("${arch}", "64"));
-		}
-		else
-		{
-			f(raw_storage, raw_dl);
+			jarlibDownloadJob->addNetAction(dl);
 		}
 	}
 	if (!brokenLocalLibs.empty())
 	{
 		jarlibDownloadJob.reset();
-		QStringList failed;
-		for (auto brokenLib : brokenLocalLibs)
-		{
-			failed.append(brokenLib->files());
-		}
-		QString failed_all = failed.join("\n");
+
+		QString failed_all = failedFiles.join("\n");
 		emitFailed(tr("Some libraries marked as 'local' are missing their jar "
 					  "files:\n%1\n\nYou'll have to correct this problem manually. If this is "
 					  "an externally tracked instance, make sure to run it at least once "
 					  "outside of MultiMC.").arg(failed_all));
 		return;
 	}
-	// TODO: think about how to propagate this from the original json file... or IF AT ALL
-	QString forgeMirrorList = "http://files.minecraftforge.net/mirror-brand.list";
-	if (!ForgeLibs.empty())
-	{
-		jarlibDownloadJob->addNetAction(
-			ForgeMirrors::make(ForgeLibs, jarlibDownloadJob, forgeMirrorList));
-	}
 
 	connect(jarlibDownloadJob.get(), SIGNAL(succeeded()), SLOT(jarlibFinished()));
 	connect(jarlibDownloadJob.get(), &NetJob::failed, this, &OneSixUpdate::jarlibFailed);
diff --git a/logic/minecraft/onesix/OneSixUpdate.h b/logic/minecraft/onesix/OneSixUpdate.h
index 6901e3d6..b5195364 100644
--- a/logic/minecraft/onesix/OneSixUpdate.h
+++ b/logic/minecraft/onesix/OneSixUpdate.h
@@ -63,6 +63,5 @@ private:
 	std::shared_ptr<Task> versionUpdateTask;
 
 	OneSixInstance *m_inst = nullptr;
-	QString jarHashOnEntry;
 	QList<FMLlib> fmlLibsToProcess;
 };
diff --git a/logic/minecraft/onesix/OneSixVersionFormat.cpp b/logic/minecraft/onesix/OneSixVersionFormat.cpp
index b5e05b22..49a18563 100644
--- a/logic/minecraft/onesix/OneSixVersionFormat.cpp
+++ b/logic/minecraft/onesix/OneSixVersionFormat.cpp
@@ -19,16 +19,16 @@ LibraryPtr OneSixVersionFormat::libraryFromJson(const QJsonObject &libObj, const
 {
 	LibraryPtr out = MojangVersionFormat::libraryFromJson(libObj, filename);
 	readString(libObj, "MMC-hint", out->m_hint);
-	readString(libObj, "MMC-absulute_url", out->m_absolute_url);
-	readString(libObj, "MMC-absoluteUrl", out->m_absolute_url);
+	readString(libObj, "MMC-absulute_url", out->m_absoluteURL);
+	readString(libObj, "MMC-absoluteUrl", out->m_absoluteURL);
 	return out;
 }
 
 QJsonObject OneSixVersionFormat::libraryToJson(Library *library)
 {
 	QJsonObject libRoot = MojangVersionFormat::libraryToJson(library);
-	if (library->m_absolute_url.size())
-		libRoot.insert("MMC-absoluteUrl", library->m_absolute_url);
+	if (library->m_absoluteURL.size())
+		libRoot.insert("MMC-absoluteUrl", library->m_absoluteURL);
 	if (library->m_hint.size())
 		libRoot.insert("MMC-hint", library->m_hint);
 	return libRoot;
@@ -64,7 +64,7 @@ VersionFilePtr OneSixVersionFormat::versionFileFromJson(const QJsonDocument &doc
 	out->name = root.value("name").toString();
 	out->fileId = root.value("fileId").toString();
 	out->version = root.value("version").toString();
-	out->mcVersion = root.value("mcVersion").toString();
+	out->dependsOnMinecraftVersion = root.value("mcVersion").toString();
 	out->filename = filename;
 
 	MojangVersionFormat::readVersionProperties(root, out.get());
@@ -167,7 +167,7 @@ QJsonDocument OneSixVersionFormat::versionFileToJson(const VersionFilePtr &patch
 	writeString(root, "name", patch->name);
 	writeString(root, "fileId", patch->fileId);
 	writeString(root, "version", patch->version);
-	writeString(root, "mcVersion", patch->mcVersion);
+	writeString(root, "mcVersion", patch->dependsOnMinecraftVersion);
 
 	MojangVersionFormat::writeVersionProperties(patch.get(), root);
 
diff --git a/logic/net/CacheDownload.cpp b/logic/net/CacheDownload.cpp
index 1d48170a..d79feb14 100644
--- a/logic/net/CacheDownload.cpp
+++ b/logic/net/CacheDownload.cpp
@@ -34,7 +34,7 @@ CacheDownload::CacheDownload(QUrl url, MetaEntryPtr entry)
 void CacheDownload::start()
 {
 	m_status = Job_InProgress;
-	if (!m_entry->stale)
+	if (!m_entry->isStale())
 	{
 		m_status = Job_Finished;
 		emit succeeded(m_index_within_job);
@@ -65,11 +65,11 @@ void CacheDownload::start()
 	QFile current(m_target_path);
 	if(current.exists() && current.size() != 0)
 	{
-		if (m_entry->remote_changed_timestamp.size())
+		if (m_entry->getRemoteChangedTimestamp().size())
 			request.setRawHeader(QString("If-Modified-Since").toLatin1(),
-								m_entry->remote_changed_timestamp.toLatin1());
-		if (m_entry->etag.size())
-			request.setRawHeader(QString("If-None-Match").toLatin1(), m_entry->etag.toLatin1());
+								m_entry->getRemoteChangedTimestamp().toLatin1());
+		if (m_entry->getETag().size())
+			request.setRawHeader(QString("If-None-Match").toLatin1(), m_entry->getETag().toLatin1());
 	}
 
 	request.setHeader(QNetworkRequest::UserAgentHeader, "MultiMC/5.0 (Cached)");
@@ -138,7 +138,7 @@ void CacheDownload::downloadFinished()
 		if (m_output_file->commit())
 		{
 			m_status = Job_Finished;
-			m_entry->md5sum = md5sum.result().toHex().constData();
+			m_entry->setMD5Sum(md5sum.result().toHex().constData());
 		}
 		else
 		{
@@ -160,14 +160,13 @@ void CacheDownload::downloadFinished()
 
 	QFileInfo output_file_info(m_target_path);
 
-	m_entry->etag = m_reply->rawHeader("ETag").constData();
+	m_entry->setETag(m_reply->rawHeader("ETag").constData());
 	if (m_reply->hasRawHeader("Last-Modified"))
 	{
-		m_entry->remote_changed_timestamp = m_reply->rawHeader("Last-Modified").constData();
+		m_entry->setRemoteChangedTimestamp(m_reply->rawHeader("Last-Modified").constData());
 	}
-	m_entry->local_changed_timestamp =
-		output_file_info.lastModified().toUTC().toMSecsSinceEpoch();
-	m_entry->stale = false;
+	m_entry->setLocalChangedTimestamp(output_file_info.lastModified().toUTC().toMSecsSinceEpoch());
+	m_entry->setStale(false);
 	ENV.metacache()->updateEntry(m_entry);
 
 	m_reply.reset();
diff --git a/logic/net/HttpMetaCache.cpp b/logic/net/HttpMetaCache.cpp
index 3d6aef0d..68bfa89c 100644
--- a/logic/net/HttpMetaCache.cpp
+++ b/logic/net/HttpMetaCache.cpp
@@ -32,7 +32,7 @@
 QString MetaEntry::getFullPath()
 {
 	// FIXME: make local?
-	return FS::PathCombine(ENV.metacache()->getBasePath(base), path);
+	return FS::PathCombine(basePath, relativePath);
 }
 
 HttpMetaCache::HttpMetaCache(QString path) : QObject()
@@ -65,8 +65,7 @@ MetaEntryPtr HttpMetaCache::getEntry(QString base, QString resource_path)
 	return MetaEntryPtr();
 }
 
-MetaEntryPtr HttpMetaCache::resolveEntry(QString base, QString resource_path,
-										 QString expected_etag)
+MetaEntryPtr HttpMetaCache::resolveEntry(QString base, QString resource_path, QString expected_etag)
 {
 	auto entry = getEntry(base, resource_path);
 	// it's not present? generate a default stale entry
@@ -114,15 +113,16 @@ MetaEntryPtr HttpMetaCache::resolveEntry(QString base, QString resource_path,
 	}
 
 	// entry passed all the checks we cared about.
+	entry->basePath = getBasePath(base);
 	return entry;
 }
 
 bool HttpMetaCache::updateEntry(MetaEntryPtr stale_entry)
 {
-	if (!m_entries.contains(stale_entry->base))
+	if (!m_entries.contains(stale_entry->baseId))
 	{
 		qCritical() << "Cannot add entry with unknown base: "
-					 << stale_entry->base.toLocal8Bit();
+					 << stale_entry->baseId.toLocal8Bit();
 		return false;
 	}
 	if (stale_entry->stale)
@@ -130,7 +130,7 @@ bool HttpMetaCache::updateEntry(MetaEntryPtr stale_entry)
 		qCritical() << "Cannot add stale entry: " << stale_entry->getFullPath().toLocal8Bit();
 		return false;
 	}
-	m_entries[stale_entry->base].entry_list[stale_entry->path] = stale_entry;
+	m_entries[stale_entry->baseId].entry_list[stale_entry->relativePath] = stale_entry;
 	SaveEventually();
 	return true;
 }
@@ -148,9 +148,10 @@ bool HttpMetaCache::evictEntry(MetaEntryPtr entry)
 
 MetaEntryPtr HttpMetaCache::staleEntry(QString base, QString resource_path)
 {
-	auto foo = new MetaEntry;
-	foo->base = base;
-	foo->path = resource_path;
+	auto foo = new MetaEntry();
+	foo->baseId = base;
+	foo->basePath = getBasePath(base);
+	foo->relativePath = resource_path;
 	foo->stale = true;
 	return MetaEntryPtr(foo);
 }
@@ -177,6 +178,9 @@ QString HttpMetaCache::getBasePath(QString base)
 
 void HttpMetaCache::Load()
 {
+	if(m_index_file.isNull())
+		return;
+
 	QFile index(m_index_file);
 	if (!index.open(QIODevice::ReadOnly))
 		return;
@@ -206,9 +210,9 @@ void HttpMetaCache::Load()
 		if (!m_entries.contains(base))
 			continue;
 		auto &entrymap = m_entries[base];
-		auto foo = new MetaEntry;
-		foo->base = base;
-		QString path = foo->path = element_obj.value("path").toString();
+		auto foo = new MetaEntry();
+		foo->baseId = base;
+		QString path = foo->relativePath = element_obj.value("path").toString();
 		foo->md5sum = element_obj.value("md5sum").toString();
 		foo->etag = element_obj.value("etag").toString();
 		foo->local_changed_timestamp = element_obj.value("last_changed_timestamp").toDouble();
@@ -229,6 +233,8 @@ void HttpMetaCache::SaveEventually()
 
 void HttpMetaCache::SaveNow()
 {
+	if(m_index_file.isNull())
+		return;
 	QJsonObject toplevel;
 	toplevel.insert("version", QJsonValue(QString("1")));
 	QJsonArray entriesArr;
@@ -242,8 +248,8 @@ void HttpMetaCache::SaveNow()
 				continue;
 			}
 			QJsonObject entryObj;
-			entryObj.insert("base", QJsonValue(entry->base));
-			entryObj.insert("path", QJsonValue(entry->path));
+			entryObj.insert("base", QJsonValue(entry->baseId));
+			entryObj.insert("path", QJsonValue(entry->relativePath));
 			entryObj.insert("md5sum", QJsonValue(entry->md5sum));
 			entryObj.insert("etag", QJsonValue(entry->etag));
 			entryObj.insert("last_changed_timestamp",
diff --git a/logic/net/HttpMetaCache.h b/logic/net/HttpMetaCache.h
index fba3fe5a..7b626c70 100644
--- a/logic/net/HttpMetaCache.h
+++ b/logic/net/HttpMetaCache.h
@@ -23,16 +23,58 @@
 
 class HttpMetaCache;
 
-struct MULTIMC_LOGIC_EXPORT MetaEntry
+class MULTIMC_LOGIC_EXPORT MetaEntry
 {
-	QString base;
-	QString path;
+friend class HttpMetaCache;
+protected:
+	MetaEntry() {}
+public:
+	bool isStale()
+	{
+		return stale;
+	}
+	void setStale(bool stale)
+	{
+		this->stale = stale;
+	}
+	QString getFullPath();
+	QString getRemoteChangedTimestamp()
+	{
+		return remote_changed_timestamp;
+	}
+	void setRemoteChangedTimestamp(QString remote_changed_timestamp)
+	{
+		this->remote_changed_timestamp = remote_changed_timestamp;
+	}
+	void setLocalChangedTimestamp(qint64 timestamp)
+	{
+		local_changed_timestamp = timestamp;
+	}
+	QString getETag()
+	{
+		return etag;
+	}
+	void setETag(QString etag)
+	{
+		this->etag = etag;
+	}
+	QString getMD5Sum()
+	{
+		return md5sum;
+	}
+	void setMD5Sum(QString md5sum)
+	{
+		this->md5sum = md5sum;
+	}
+protected:
+	QString baseId;
+	QString basePath;
+	QString relativePath;
 	QString md5sum;
 	QString etag;
 	qint64 local_changed_timestamp = 0;
 	QString remote_changed_timestamp; // QString for now, RFC 2822 encoded time
 	bool stale = true;
-	QString getFullPath();
 };
 
 typedef std::shared_ptr<MetaEntry> MetaEntryPtr;
@@ -42,7 +84,7 @@ class MULTIMC_LOGIC_EXPORT HttpMetaCache : public QObject
 	Q_OBJECT
 public:
 	// supply path to the cache index file
-	HttpMetaCache(QString path);
+	HttpMetaCache(QString path = QString());
 	~HttpMetaCache();
 
 	// get the entry solely from the cache
@@ -80,4 +122,4 @@ private:
 	QMap<QString, EntryMap> m_entries;
 	QString m_index_file;
 	QTimer saveBatchingTimer;
-};
\ No newline at end of file
+};
diff --git a/logic/net/URLConstants.cpp b/logic/net/URLConstants.cpp
index 85224767..bd476b2c 100644
--- a/logic/net/URLConstants.cpp
+++ b/logic/net/URLConstants.cpp
@@ -1,24 +1,16 @@
 #include "URLConstants.h"
-namespace URLConstants
+
+namespace URLConstants {
+
+QString getLegacyJarUrl(QString version)
 {
-const QString AWS_DOWNLOAD_BASE("s3.amazonaws.com/Minecraft.Download/");
-const QString AWS_DOWNLOAD_VERSIONS(AWS_DOWNLOAD_BASE + "versions/");
-const QString AWS_DOWNLOAD_LIBRARIES(AWS_DOWNLOAD_BASE + "libraries/");
-const QString AWS_DOWNLOAD_INDEXES(AWS_DOWNLOAD_BASE + "indexes/");
-const QString ASSETS_BASE("assets.minecraft.net/");
-const QString RESOURCE_BASE("resources.download.minecraft.net/");
-const QString LIBRARY_BASE("libraries.minecraft.net/");
-//const QString SKINS_BASE("skins.minecraft.net/MinecraftSkins/");
-const QString SKINS_BASE("crafatar.com/skins/");
-const QString AUTH_BASE("authserver.mojang.com/");
-const QString FORGE_LEGACY_URL("http://files.minecraftforge.net/minecraftforge/json");
-const QString
-	FORGE_GRADLE_URL("http://files.minecraftforge.net/maven/net/minecraftforge/forge/json");
-const QString MOJANG_STATUS_URL("http://status.mojang.com/check");
-const QString MOJANG_STATUS_NEWS_URL("http://status.mojang.com/news");
-const QString LITELOADER_URL("http://dl.liteloader.com/versions/versions.json");
-const QString IMGUR_BASE_URL("https://api.imgur.com/3/");
-const QString FMLLIBS_OUR_BASE_URL("http://files.multimc.org/fmllibs/");
-const QString FMLLIBS_FORGE_BASE_URL("http://files.minecraftforge.net/fmllibs/");
-const QString TRANSLATIONS_BASE_URL("http://files.multimc.org/translations/");
+	return "http://" + AWS_DOWNLOAD_VERSIONS + getJarPath(version);
+}
+
+QString getJarPath(QString version)
+{
+	return version + "/" + version + ".jar";
+}
+
+
 }
diff --git a/logic/net/URLConstants.h b/logic/net/URLConstants.h
index b04f44ba..8923ef54 100644
--- a/logic/net/URLConstants.h
+++ b/logic/net/URLConstants.h
@@ -17,26 +17,24 @@
 
 #include <QString>
 
-#include "multimc_logic_export.h"
-
 namespace URLConstants
 {
-extern const QString AWS_DOWNLOAD_BASE;
-extern const QString AWS_DOWNLOAD_VERSIONS;
-extern const QString AWS_DOWNLOAD_LIBRARIES;
-extern const QString AWS_DOWNLOAD_INDEXES;
-extern const QString ASSETS_BASE;
-extern const QString RESOURCE_BASE;
-extern const QString LIBRARY_BASE;
-MULTIMC_LOGIC_EXPORT extern const QString SKINS_BASE;
-extern const QString AUTH_BASE;
-extern const QString FORGE_LEGACY_URL;
-extern const QString FORGE_GRADLE_URL;
-extern const QString MOJANG_STATUS_URL;
-extern const QString MOJANG_STATUS_NEWS_URL;
-extern const QString LITELOADER_URL;
-extern const QString IMGUR_BASE_URL;
-extern const QString FMLLIBS_OUR_BASE_URL;
-extern const QString FMLLIBS_FORGE_BASE_URL;
-extern const QString TRANSLATIONS_BASE_URL;
+const QString AWS_DOWNLOAD_VERSIONS("s3.amazonaws.com/Minecraft.Download/versions/");
+const QString RESOURCE_BASE("resources.download.minecraft.net/");
+const QString LIBRARY_BASE("libraries.minecraft.net/");
+//const QString SKINS_BASE("skins.minecraft.net/MinecraftSkins/");
+const QString SKINS_BASE("crafatar.com/skins/");
+const QString AUTH_BASE("authserver.mojang.com/");
+const QString FORGE_LEGACY_URL("http://files.minecraftforge.net/minecraftforge/json");
+const QString FORGE_GRADLE_URL("http://files.minecraftforge.net/maven/net/minecraftforge/forge/json");
+const QString MOJANG_STATUS_URL("http://status.mojang.com/check");
+const QString MOJANG_STATUS_NEWS_URL("http://status.mojang.com/news");
+const QString LITELOADER_URL("http://dl.liteloader.com/versions/versions.json");
+const QString IMGUR_BASE_URL("https://api.imgur.com/3/");
+const QString FMLLIBS_OUR_BASE_URL("http://files.multimc.org/fmllibs/");
+const QString FMLLIBS_FORGE_BASE_URL("http://files.minecraftforge.net/fmllibs/");
+const QString TRANSLATIONS_BASE_URL("http://files.multimc.org/translations/");
+
+QString getJarPath(QString version);
+QString getLegacyJarUrl(QString version);
 }
diff --git a/logic/notifications/NotificationChecker.cpp b/logic/notifications/NotificationChecker.cpp
index 4e35cacc..ab2570b7 100644
--- a/logic/notifications/NotificationChecker.cpp
+++ b/logic/notifications/NotificationChecker.cpp
@@ -54,7 +54,7 @@ void NotificationChecker::checkForNotifications()
 	}
 	m_checkJob.reset(new NetJob("Checking for notifications"));
 	auto entry = ENV.metacache()->resolveEntry("root", "notifications.json");
-	entry->stale = true;
+	entry->setStale(true);
 	m_checkJob->addNetAction(m_download = CacheDownload::make(m_notificationsUrl, entry));
 	connect(m_download.get(), &CacheDownload::succeeded, this,
 			&NotificationChecker::downloadSucceeded);
diff --git a/logic/trans/TranslationDownloader.cpp b/logic/trans/TranslationDownloader.cpp
index 5a9cde12..ee5c1fd2 100644
--- a/logic/trans/TranslationDownloader.cpp
+++ b/logic/trans/TranslationDownloader.cpp
@@ -28,7 +28,7 @@ void TranslationDownloader::indexRecieved()
 		if (!line.isEmpty())
 		{
 			MetaEntryPtr entry = ENV.metacache()->resolveEntry("translations", "mmc_" + line);
-			entry->stale = true;
+			entry->setStale(true);
 			CacheDownloadPtr dl = CacheDownload::make(
 				QUrl(URLConstants::TRANSLATIONS_BASE_URL + line),
 				entry);
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index 1061f911..67a7a45e 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -27,6 +27,7 @@ add_unit_test(userutils tst_userutils.cpp)
 add_unit_test(modutils tst_modutils.cpp)
 add_unit_test(inifile tst_inifile.cpp)
 add_unit_test(FileSystem tst_FileSystem.cpp)
+add_unit_test(Library tst_Library.cpp)
 add_unit_test(UpdateChecker tst_UpdateChecker.cpp)
 add_unit_test(DownloadTask tst_DownloadTask.cpp)
 add_unit_test(filematchers tst_filematchers.cpp)
diff --git a/tests/data/lib-native-arch.json b/tests/data/lib-native-arch.json
new file mode 100644
index 00000000..a73aac54
--- /dev/null
+++ b/tests/data/lib-native-arch.json
@@ -0,0 +1,46 @@
+{
+	"downloads": {
+		"classifiers": {
+			"natives-osx": {
+				"path": "tv/twitch/twitch-platform/5.16/twitch-platform-5.16-natives-osx.jar",
+				"sha1": "62503ee712766cf77f97252e5902786fd834b8c5",
+				"size": 418331,
+				"url": "https://libraries.minecraft.net/tv/twitch/twitch-platform/5.16/twitch-platform-5.16-natives-osx.jar"
+			},
+			"natives-windows-32": {
+				"path": "tv/twitch/twitch-platform/5.16/twitch-platform-5.16-natives-windows-32.jar",
+				"sha1": "7c6affe439099806a4f552da14c42f9d643d8b23",
+				"size": 386792,
+				"url": "https://libraries.minecraft.net/tv/twitch/twitch-platform/5.16/twitch-platform-5.16-natives-windows-32.jar"
+			},
+			"natives-windows-64": {
+				"path": "tv/twitch/twitch-platform/5.16/twitch-platform-5.16-natives-windows-64.jar",
+				"sha1": "39d0c3d363735b4785598e0e7fbf8297c706a9f9",
+				"size": 463390,
+				"url": "https://libraries.minecraft.net/tv/twitch/twitch-platform/5.16/twitch-platform-5.16-natives-windows-64.jar"
+			}
+		}
+	},
+	"extract": {
+		"exclude": [
+			"META-INF/"
+		]
+	},
+	"name": "tv.twitch:twitch-platform:5.16",
+	"natives": {
+		"linux": "natives-linux",
+		"osx": "natives-osx",
+		"windows": "natives-windows-${arch}"
+	},
+	"rules": [
+		{
+			"action": "allow"
+		},
+		{
+			"action": "disallow",
+			"os": {
+				"name": "linux"
+			}
+		}
+	]
+}
diff --git a/tests/data/lib-native.json b/tests/data/lib-native.json
new file mode 100644
index 00000000..0a95b2b9
--- /dev/null
+++ b/tests/data/lib-native.json
@@ -0,0 +1,52 @@
+{
+	"downloads": {
+		"artifact": {
+			"path": "org/lwjgl/lwjgl/lwjgl-platform/2.9.4-nightly-20150209/lwjgl-platform-2.9.4-nightly-20150209.jar",
+			"sha1": "b04f3ee8f5e43fa3b162981b50bb72fe1acabb33",
+			"size": 22,
+			"url": "https://libraries.minecraft.net/org/lwjgl/lwjgl/lwjgl-platform/2.9.4-nightly-20150209/lwjgl-platform-2.9.4-nightly-20150209.jar"
+		},
+		"classifiers": {
+			"natives-linux": {
+				"path": "org/lwjgl/lwjgl/lwjgl-platform/2.9.4-nightly-20150209/lwjgl-platform-2.9.4-nightly-20150209-natives-linux.jar",
+				"sha1": "931074f46c795d2f7b30ed6395df5715cfd7675b",
+				"size": 578680,
+				"url": "https://libraries.minecraft.net/org/lwjgl/lwjgl/lwjgl-platform/2.9.4-nightly-20150209/lwjgl-platform-2.9.4-nightly-20150209-natives-linux.jar"
+			},
+			"natives-osx": {
+				"path": "org/lwjgl/lwjgl/lwjgl-platform/2.9.4-nightly-20150209/lwjgl-platform-2.9.4-nightly-20150209-natives-osx.jar",
+				"sha1": "bcab850f8f487c3f4c4dbabde778bb82bd1a40ed",
+				"size": 426822,
+				"url": "https://libraries.minecraft.net/org/lwjgl/lwjgl/lwjgl-platform/2.9.4-nightly-20150209/lwjgl-platform-2.9.4-nightly-20150209-natives-osx.jar"
+			},
+			"natives-windows": {
+				"path": "org/lwjgl/lwjgl/lwjgl-platform/2.9.4-nightly-20150209/lwjgl-platform-2.9.4-nightly-20150209-natives-windows.jar",
+				"sha1": "b84d5102b9dbfabfeb5e43c7e2828d98a7fc80e0",
+				"size": 613748,
+				"url": "https://libraries.minecraft.net/org/lwjgl/lwjgl/lwjgl-platform/2.9.4-nightly-20150209/lwjgl-platform-2.9.4-nightly-20150209-natives-windows.jar"
+			}
+		}
+	},
+	"extract": {
+		"exclude": [
+			"META-INF/"
+		]
+	},
+	"name": "org.lwjgl.lwjgl:lwjgl-platform:2.9.4-nightly-20150209",
+	"natives": {
+		"linux": "natives-linux",
+		"osx": "natives-osx",
+		"windows": "natives-windows"
+	},
+	"rules": [
+		{
+			"action": "allow"
+		},
+		{
+			"action": "disallow",
+			"os": {
+				"name": "osx"
+			}
+		}
+	]
+}
diff --git a/tests/data/lib-simple.json b/tests/data/lib-simple.json
new file mode 100644
index 00000000..3ef0f490
--- /dev/null
+++ b/tests/data/lib-simple.json
@@ -0,0 +1,11 @@
+{
+	"downloads": {
+		"artifact": {
+			"path": "com/paulscode/codecwav/20101023/codecwav-20101023.jar",
+			"sha1": "12f031cfe88fef5c1dd36c563c0a3a69bd7261da",
+			"size": 5618,
+			"url": "https://libraries.minecraft.net/com/paulscode/codecwav/20101023/codecwav-20101023.jar"
+		}
+	},
+	"name": "com.paulscode:codecwav:20101023"
+}
diff --git a/tests/tst_Library.cpp b/tests/tst_Library.cpp
new file mode 100644
index 00000000..b5840261
--- /dev/null
+++ b/tests/tst_Library.cpp
@@ -0,0 +1,195 @@
+#include <QTest>
+#include "TestUtil.h"
+
+#include "minecraft/MojangVersionFormat.h"
+#include "minecraft/onesix/OneSixVersionFormat.h"
+#include "minecraft/Library.h"
+#include "net/HttpMetaCache.h"
+#include "FileSystem.h"
+
+class LibraryTest : public QObject
+{
+	Q_OBJECT
+private:
+	LibraryPtr readMojangJson(const char *file)
+	{
+		auto path = QFINDTESTDATA(file);
+		QFile jsonFile(path);
+		jsonFile.open(QIODevice::ReadOnly);
+		auto data = jsonFile.readAll();
+		jsonFile.close();
+		return MojangVersionFormat::libraryFromJson(QJsonDocument::fromJson(data).object(), file);
+	}
+	// get absolute path to expected storage, assuming default cache prefix
+	QStringList getStorage(QString relative)
+	{
+		return {FS::PathCombine(cache->getBasePath("libraries"), relative)};
+	}
+private
+slots:
+	void initTestCase()
+	{
+		cache.reset(new HttpMetaCache());
+		cache->addBase("libraries", QDir("libraries").absolutePath());
+	}
+	void test_legacy()
+	{
+		Library test("test.package:testname:testversion");
+		QCOMPARE(test.artifactPrefix(), QString("test.package:testname"));
+		QCOMPARE(test.isNative(), false);
+
+		QStringList jar, native, native32, native64;
+		test.getApplicableFiles(currentSystem, jar, native, native32, native64);
+		QCOMPARE(jar, getStorage("test/package/testname/testversion/testname-testversion.jar"));
+		QCOMPARE(native, {});
+		QCOMPARE(native32, {});
+		QCOMPARE(native64, {});
+	}
+	void test_legacy_url()
+	{
+		QStringList failedFiles;
+		Library test("test.package:testname:testversion");
+		test.setRepositoryURL("file://foo/bar");
+		auto downloads = test.getDownloads(currentSystem, cache.get(), failedFiles);
+		QCOMPARE(downloads.size(), 1);
+		QCOMPARE(failedFiles, {});
+		NetActionPtr dl = downloads[0];
+		QCOMPARE(dl->m_url, QUrl("file://foo/bar/test/package/testname/testversion/testname-testversion.jar"));
+	}
+	void test_legacy_url_local_broken()
+	{
+		Library test("test.package:testname:testversion");
+		QCOMPARE(test.isNative(), false);
+		QStringList failedFiles;
+		test.setHint("local");
+		auto downloads = test.getDownloads(currentSystem, cache.get(), failedFiles);
+		QCOMPARE(downloads.size(), 0);
+		QCOMPARE(failedFiles, getStorage("test/package/testname/testversion/testname-testversion.jar"));
+	}
+	void test_legacy_native()
+	{
+		Library test("test.package:testname:testversion");
+		test.m_nativeClassifiers[OpSys::Os_Linux]="linux";
+		QCOMPARE(test.isNative(), true);
+		test.setRepositoryURL("file://foo/bar");
+		{
+			QStringList jar, native, native32, native64;
+			test.getApplicableFiles(Os_Linux, jar, native, native32, native64);
+			QCOMPARE(jar, {});
+			QCOMPARE(native, getStorage("test/package/testname/testversion/testname-testversion-linux.jar"));
+			QCOMPARE(native32, {});
+			QCOMPARE(native64, {});
+			QStringList failedFiles;
+			auto dls = test.getDownloads(Os_Linux, cache.get(), failedFiles);
+			QCOMPARE(dls.size(), 1);
+			QCOMPARE(failedFiles, {});
+			auto dl = dls[0];
+			QCOMPARE(dl->m_url, QUrl("file://foo/bar/test/package/testname/testversion/testname-testversion-linux.jar"));
+		}
+	}
+	void test_legacy_native_arch()
+	{
+		Library test("test.package:testname:testversion");
+		test.m_nativeClassifiers[OpSys::Os_Linux]="linux-${arch}";
+		test.m_nativeClassifiers[OpSys::Os_OSX]="osx-${arch}";
+		test.m_nativeClassifiers[OpSys::Os_Windows]="windows-${arch}";
+		QCOMPARE(test.isNative(), true);
+		test.setRepositoryURL("file://foo/bar");
+		{
+			QStringList jar, native, native32, native64;
+			test.getApplicableFiles(Os_Linux, jar, native, native32, native64);
+			QCOMPARE(jar, {});
+			QCOMPARE(native, {});
+			QCOMPARE(native32, getStorage("test/package/testname/testversion/testname-testversion-linux-32.jar"));
+			QCOMPARE(native64, getStorage("test/package/testname/testversion/testname-testversion-linux-64.jar"));
+			QStringList failedFiles;
+			auto dls = test.getDownloads(Os_Linux, cache.get(), failedFiles);
+			QCOMPARE(dls.size(), 2);
+			QCOMPARE(failedFiles, {});
+			QCOMPARE(dls[0]->m_url, QUrl("file://foo/bar/test/package/testname/testversion/testname-testversion-linux-32.jar"));
+			QCOMPARE(dls[1]->m_url, QUrl("file://foo/bar/test/package/testname/testversion/testname-testversion-linux-64.jar"));
+		}
+		{
+			QStringList jar, native, native32, native64;
+			test.getApplicableFiles(Os_Windows, jar, native, native32, native64);
+			QCOMPARE(jar, {});
+			QCOMPARE(native, {});
+			QCOMPARE(native32, getStorage("test/package/testname/testversion/testname-testversion-windows-32.jar"));
+			QCOMPARE(native64, getStorage("test/package/testname/testversion/testname-testversion-windows-64.jar"));
+			QStringList failedFiles;
+			auto dls = test.getDownloads(Os_Windows, cache.get(), failedFiles);
+			QCOMPARE(dls.size(), 2);
+			QCOMPARE(failedFiles, {});
+			QCOMPARE(dls[0]->m_url, QUrl("file://foo/bar/test/package/testname/testversion/testname-testversion-windows-32.jar"));
+			QCOMPARE(dls[1]->m_url, QUrl("file://foo/bar/test/package/testname/testversion/testname-testversion-windows-64.jar"));
+		}
+		{
+			QStringList jar, native, native32, native64;
+			test.getApplicableFiles(Os_OSX, jar, native, native32, native64);
+			QCOMPARE(jar, {});
+			QCOMPARE(native, {});
+			QCOMPARE(native32, getStorage("test/package/testname/testversion/testname-testversion-osx-32.jar"));
+			QCOMPARE(native64, getStorage("test/package/testname/testversion/testname-testversion-osx-64.jar"));
+			QStringList failedFiles;
+			auto dls = test.getDownloads(Os_OSX, cache.get(), failedFiles);
+			QCOMPARE(dls.size(), 2);
+			QCOMPARE(failedFiles, {});
+			QCOMPARE(dls[0]->m_url, QUrl("file://foo/bar/test/package/testname/testversion/testname-testversion-osx-32.jar"));
+			QCOMPARE(dls[1]->m_url, QUrl("file://foo/bar/test/package/testname/testversion/testname-testversion-osx-64.jar"));
+		}
+	}
+	void test_onenine()
+	{
+		auto test = readMojangJson("data/lib-simple.json");
+		QStringList jar, native, native32, native64;
+		test->getApplicableFiles(Os_OSX, jar, native, native32, native64);
+		QCOMPARE(jar, getStorage("com/paulscode/codecwav/20101023/codecwav-20101023.jar"));
+		QCOMPARE(native, {});
+		QCOMPARE(native32, {});
+		QCOMPARE(native64, {});
+		QStringList failedFiles;
+		auto dls = test->getDownloads(Os_Linux, cache.get(), failedFiles);
+		QCOMPARE(dls.size(), 1);
+		QCOMPARE(failedFiles, {});
+		QCOMPARE(dls[0]->m_url, QUrl("https://libraries.minecraft.net/com/paulscode/codecwav/20101023/codecwav-20101023.jar"));
+	}
+	void test_onenine_native()
+	{
+		auto test = readMojangJson("data/lib-native.json");
+		QStringList jar, native, native32, native64;
+		test->getApplicableFiles(Os_OSX, jar, native, native32, native64);
+		QCOMPARE(jar, getStorage("org/lwjgl/lwjgl/lwjgl-platform/2.9.4-nightly-20150209/lwjgl-platform-2.9.4-nightly-20150209.jar"));
+		QCOMPARE(native, getStorage("org/lwjgl/lwjgl/lwjgl-platform/2.9.4-nightly-20150209/lwjgl-platform-2.9.4-nightly-20150209-natives-osx.jar"));
+		QCOMPARE(native32, {});
+		QCOMPARE(native64, {});
+		QStringList failedFiles;
+		auto dls = test->getDownloads(Os_OSX, cache.get(), failedFiles);
+		QCOMPARE(dls.size(), 2);
+		QCOMPARE(failedFiles, {});
+		QCOMPARE(dls[0]->m_url, QUrl("https://libraries.minecraft.net/org/lwjgl/lwjgl/lwjgl-platform/2.9.4-nightly-20150209/lwjgl-platform-2.9.4-nightly-20150209.jar"));
+		QCOMPARE(dls[1]->m_url, QUrl("https://libraries.minecraft.net/org/lwjgl/lwjgl/lwjgl-platform/2.9.4-nightly-20150209/lwjgl-platform-2.9.4-nightly-20150209-natives-osx.jar"));
+	}
+	void test_onenine_native_arch()
+	{
+		auto test = readMojangJson("data/lib-native-arch.json");
+		QStringList jar, native, native32, native64;
+		test->getApplicableFiles(Os_Windows, jar, native, native32, native64);
+		QCOMPARE(jar, {});
+		QCOMPARE(native, {});
+		QCOMPARE(native32, getStorage("tv/twitch/twitch-platform/5.16/twitch-platform-5.16-natives-windows-32.jar"));
+		QCOMPARE(native64, getStorage("tv/twitch/twitch-platform/5.16/twitch-platform-5.16-natives-windows-64.jar"));
+		QStringList failedFiles;
+		auto dls = test->getDownloads(Os_Windows, cache.get(), failedFiles);
+		QCOMPARE(dls.size(), 2);
+		QCOMPARE(failedFiles, {});
+		QCOMPARE(dls[0]->m_url, QUrl("https://libraries.minecraft.net/tv/twitch/twitch-platform/5.16/twitch-platform-5.16-natives-windows-32.jar"));
+		QCOMPARE(dls[1]->m_url, QUrl("https://libraries.minecraft.net/tv/twitch/twitch-platform/5.16/twitch-platform-5.16-natives-windows-64.jar"));
+	}
+private:
+	std::unique_ptr<HttpMetaCache> cache;
+	QString workDir;
+};
+
+QTEST_GUILESS_MAIN(LibraryTest)
+
+#include "tst_Library.moc"