diff --git a/logic/CMakeLists.txt b/logic/CMakeLists.txt
index fe827f5f..28c1b8fc 100644
--- a/logic/CMakeLists.txt
+++ b/logic/CMakeLists.txt
@@ -186,8 +186,8 @@ set(LOGIC_SOURCES
 	minecraft/MinecraftVersionList.cpp
 	minecraft/MinecraftVersionList.h
 	minecraft/NullProfileStrategy.h
-	minecraft/OneSixRule.cpp
-	minecraft/OneSixRule.h
+	minecraft/Rule.cpp
+	minecraft/Rule.h
 	minecraft/OpSys.cpp
 	minecraft/OpSys.h
 	minecraft/ParseUtils.cpp
@@ -195,8 +195,9 @@ set(LOGIC_SOURCES
 	minecraft/ProfileUtils.cpp
 	minecraft/ProfileUtils.h
 	minecraft/ProfileStrategy.h
-	minecraft/RawLibrary.cpp
-	minecraft/RawLibrary.h
+	minecraft/Library.cpp
+	minecraft/Library.h
+	minecraft/MojangDownloadInfo.h
 	minecraft/VersionBuildError.h
 	minecraft/VersionFile.cpp
 	minecraft/VersionFile.h
diff --git a/logic/minecraft/RawLibrary.cpp b/logic/minecraft/Library.cpp
similarity index 81%
rename from logic/minecraft/RawLibrary.cpp
rename to logic/minecraft/Library.cpp
index 735f5b0a..9a1d2cc7 100644
--- a/logic/minecraft/RawLibrary.cpp
+++ b/logic/minecraft/Library.cpp
@@ -1,7 +1,7 @@
-#include "RawLibrary.h"
+#include "Library.h"
 #include <FileSystem.h>
 
-QStringList RawLibrary::files() const
+QStringList Library::files() const
 {
 	QStringList retval;
 	QString storage = storageSuffix();
@@ -19,7 +19,7 @@ QStringList RawLibrary::files() const
 	return retval;
 }
 
-bool RawLibrary::filesExist(const QDir &base) const
+bool Library::filesExist(const QDir &base) const
 {
 	auto libFiles = files();
 	for(auto file: libFiles)
@@ -32,7 +32,7 @@ bool RawLibrary::filesExist(const QDir &base) const
 	return true;
 }
 
-QString RawLibrary::url() const
+QString Library::url() const
 {
 	if (!m_absolute_url.isEmpty())
 	{
@@ -54,7 +54,7 @@ QString RawLibrary::url() const
 	}
 }
 
-bool RawLibrary::isActive() const
+bool Library::isActive() const
 {
 	bool result = true;
 	if (m_rules.empty())
@@ -79,17 +79,17 @@ bool RawLibrary::isActive() const
 	return result;
 }
 
-void RawLibrary::setStoragePrefix(QString prefix)
+void Library::setStoragePrefix(QString prefix)
 {
 	m_storagePrefix = prefix;
 }
 
-QString RawLibrary::defaultStoragePrefix()
+QString Library::defaultStoragePrefix()
 {
 	return "libraries/";
 }
 
-QString RawLibrary::storagePrefix() const
+QString Library::storagePrefix() const
 {
 	if(m_storagePrefix.isEmpty())
 	{
@@ -98,7 +98,7 @@ QString RawLibrary::storagePrefix() const
 	return m_storagePrefix;
 }
 
-QString RawLibrary::storageSuffix() const
+QString Library::storageSuffix() const
 {
 	// non-native? use only the gradle specifier
 	if (!isNative())
@@ -119,12 +119,12 @@ QString RawLibrary::storageSuffix() const
 	return nativeSpec.toPath();
 }
 
-QString RawLibrary::storagePath() const
+QString Library::storagePath() const
 {
 	return FS::PathCombine(storagePrefix(), storageSuffix());
 }
 
-bool RawLibrary::storagePathIsDefault() const
+bool Library::storagePathIsDefault() const
 {
 	return m_storagePrefix.isEmpty();
 }
diff --git a/logic/minecraft/RawLibrary.h b/logic/minecraft/Library.h
similarity index 90%
rename from logic/minecraft/RawLibrary.h
rename to logic/minecraft/Library.h
index a8d3ef0d..7ae126a9 100644
--- a/logic/minecraft/RawLibrary.h
+++ b/logic/minecraft/Library.h
@@ -8,30 +8,31 @@
 #include <QUrl>
 #include <memory>
 
-#include "OneSixRule.h"
+#include "Rule.h"
 #include "minecraft/OpSys.h"
 #include "GradleSpecifier.h"
+#include "MojangDownloadInfo.h"
 #include "net/URLConstants.h"
 
-class RawLibrary;
-typedef std::shared_ptr<RawLibrary> RawLibraryPtr;
+class Library;
+typedef std::shared_ptr<Library> LibraryPtr;
 
-class RawLibrary
+class Library
 {
 	friend class OneSixVersionFormat;
 	friend class MojangVersionFormat;
 public:
-	RawLibrary()
+	Library()
 	{
 	}
-	RawLibrary(const QString &name)
+	Library(const QString &name)
 	{
 		m_name = name;
 	}
 	/// limited copy without some data. TODO: why?
-	static RawLibraryPtr limitedCopy(RawLibraryPtr base)
+	static LibraryPtr limitedCopy(LibraryPtr base)
 	{
-		auto newlib = std::make_shared<RawLibrary>();
+		auto newlib = std::make_shared<Library>();
 		newlib->m_name = base->m_name;
 		newlib->m_base_url = base->m_base_url;
 		newlib->m_hint = base->m_hint;
@@ -158,7 +159,6 @@ protected: /* data */
 	/// DEPRECATED: MultiMC-specific absolute URL. takes precedence over the implicit maven repo URL, if defined
 	QString m_absolute_url;
 
-public: /* data */
 	/**
 	 * MultiMC-specific type hint - modifies how the library is treated
 	 */
@@ -166,7 +166,7 @@ public: /* data */
 
 	/**
 	 * storage - by default the local libraries folder in multimc, but could be elsewhere
-	 * MultiMC specific, because of FTB. 
+	 * MultiMC specific, because of FTB.
 	 */
 	QString m_storagePrefix;
 
@@ -184,4 +184,7 @@ public: /* data */
 
 	/// rules associated with the library
 	QList<std::shared_ptr<Rule>> m_rules;
+
+	/// MOJANG: container with Mojang style download info
+	MojangLibraryDownloadInfoPtr m_mojang_downloads;
 };
diff --git a/logic/minecraft/MinecraftProfile.cpp b/logic/minecraft/MinecraftProfile.cpp
index be847050..0cf8b548 100644
--- a/logic/minecraft/MinecraftProfile.cpp
+++ b/logic/minecraft/MinecraftProfile.cpp
@@ -230,9 +230,9 @@ bool MinecraftProfile::revertToVanilla()
 	return true;
 }
 
-QList<std::shared_ptr<RawLibrary> > MinecraftProfile::getActiveNormalLibs()
+QList<std::shared_ptr<Library> > MinecraftProfile::getActiveNormalLibs()
 {
-	QList<std::shared_ptr<RawLibrary> > output;
+	QList<std::shared_ptr<Library> > output;
 	for (auto lib : libraries)
 	{
 		if (lib->isActive() && !lib->isNative())
@@ -251,9 +251,9 @@ QList<std::shared_ptr<RawLibrary> > MinecraftProfile::getActiveNormalLibs()
 	return output;
 }
 
-QList<std::shared_ptr<RawLibrary> > MinecraftProfile::getActiveNativeLibs()
+QList<std::shared_ptr<Library> > MinecraftProfile::getActiveNativeLibs()
 {
-	QList<std::shared_ptr<RawLibrary> > output;
+	QList<std::shared_ptr<Library> > output;
 	for (auto lib : libraries)
 	{
 		if (lib->isActive() && lib->isNative())
diff --git a/logic/minecraft/MinecraftProfile.h b/logic/minecraft/MinecraftProfile.h
index 25663c74..84d3ce3b 100644
--- a/logic/minecraft/MinecraftProfile.h
+++ b/logic/minecraft/MinecraftProfile.h
@@ -21,7 +21,7 @@
 #include <QList>
 #include <memory>
 
-#include "RawLibrary.h"
+#include "Library.h"
 #include "VersionFile.h"
 #include "JarMod.h"
 
@@ -93,10 +93,10 @@ public:
 
 public:
 	/// get all java libraries that belong to the classpath
-	QList<RawLibraryPtr> getActiveNormalLibs();
+	QList<LibraryPtr> getActiveNormalLibs();
 
 	/// get all native libraries that need to be available to the process
-	QList<RawLibraryPtr> getActiveNativeLibs();
+	QList<LibraryPtr> getActiveNativeLibs();
 
 	/// get file ID of the patch file at #
 	QString versionFileId(const int index) const;
@@ -161,10 +161,10 @@ public: /* data */
 	QString appletClass;
 
 	/// the list of libs - both active and inactive, native and java
-	QList<RawLibraryPtr> libraries;
+	QList<LibraryPtr> libraries;
 
 	/// same, but only vanilla.
-	QList<RawLibraryPtr> vanillaLibraries;
+	QList<LibraryPtr> vanillaLibraries;
 
 	/// traits, collected from all the version files (version files can only add)
 	QSet<QString> traits;
diff --git a/logic/minecraft/MojangDownloadInfo.h b/logic/minecraft/MojangDownloadInfo.h
new file mode 100644
index 00000000..780318b8
--- /dev/null
+++ b/logic/minecraft/MojangDownloadInfo.h
@@ -0,0 +1,92 @@
+#pragma once
+#include <QString>
+#include <memory>
+
+class MojangDownloadInfo
+{
+	friend class MojangVersionFormat;
+public:
+	QString getUrl()
+	{
+		return m_url;
+	}
+
+	QString getSha1()
+	{
+		return m_sha1;
+	}
+
+	int getSize()
+	{
+		return m_size;
+	}
+
+protected:
+	/// Local filesystem path. WARNING: not used, only here so we can pass through mojang files unmolested!
+	QString m_path;
+	/// absolute URL of this file
+	QString m_url;
+	/// sha-1 checksum of the file
+	QString m_sha1;
+	/// size of the file in bytes
+	int m_size;
+};
+
+typedef std::shared_ptr<MojangDownloadInfo> MojangDownloadInfoPtr;
+
+class MojangLibraryDownloadInfo
+{
+	friend class MojangVersionFormat;
+public:
+	MojangDownloadInfo *getDownloadInfo(QString classifier)
+	{
+		if (classifier.isNull())
+		{
+			return artifact.get();
+		}
+		
+		return classifiers[classifier].get();
+	}
+private:
+	MojangDownloadInfoPtr artifact;
+	QMap<QString, MojangDownloadInfoPtr> classifiers;
+};
+
+typedef std::shared_ptr<MojangLibraryDownloadInfo> MojangLibraryDownloadInfoPtr;
+
+class MojangAssetIndexInfo : public MojangDownloadInfo
+{
+	friend class MojangVersionFormat;
+public:
+	MojangAssetIndexInfo()
+	{
+	}
+
+	MojangAssetIndexInfo(QString id)
+	{
+		m_id = id;
+		m_url = "https://s3.amazonaws.com/Minecraft.Download/indexes/" + id + ".json";
+		m_known = false;
+	}
+
+	int getTotalSize()
+	{
+		return m_totalSize;
+	}
+
+	QString getId()
+	{
+		return m_id;
+	}
+
+	bool sizeAndHashKnown()
+	{
+		return m_known;
+	}
+
+protected:
+	int m_totalSize;
+	QString m_id;
+	bool m_known = true;
+};
+typedef std::shared_ptr<MojangAssetIndexInfo> MojangAssetIndexInfoPtr;
diff --git a/logic/minecraft/MojangVersionFormat.cpp b/logic/minecraft/MojangVersionFormat.cpp
index 4d6f205b..1b95a0ba 100644
--- a/logic/minecraft/MojangVersionFormat.cpp
+++ b/logic/minecraft/MojangVersionFormat.cpp
@@ -18,6 +18,37 @@ static void readString(const QJsonObject &root, const QString &key, QString &var
 	}
 }
 
+MojangAssetIndexInfoPtr MojangVersionFormat::assetIndexFromJson(const QJsonObject &obj)
+{
+	auto out = std::make_shared<MojangAssetIndexInfo>();
+	// optional, not used
+	readString(obj, "path", out->m_path);
+	// required!
+	out->m_sha1 = requireString(obj, "sha1");
+	out->m_url = requireString(obj, "url");
+	out->m_size = requireInteger(obj, "size");
+	out->m_totalSize = requireInteger(obj, "totalSize");
+	out->m_id = requireString(obj, "id");
+	// out->m_known = true;
+	return out;
+}
+
+QJsonObject MojangVersionFormat::assetIndexToJson(MojangAssetIndexInfoPtr info)
+{
+	QJsonObject out;
+	if(!info->m_path.isNull())
+	{
+		out.insert("path", info->m_path);
+	}
+	out.insert("sha1", info->m_sha1);
+	out.insert("size", info->m_size);
+	out.insert("url", info->m_url);
+	out.insert("totalSize", info->m_totalSize);
+	out.insert("id", info->m_id);
+	return out;
+}
+
+
 VersionFilePtr MojangVersionFormat::versionFileFromJson(const QJsonDocument &doc, const QString &filename)
 {
 	VersionFilePtr out(new VersionFile());
@@ -43,6 +74,10 @@ VersionFilePtr MojangVersionFormat::versionFileFromJson(const QJsonDocument &doc
 	readString(root, "minecraftArguments", out->overwriteMinecraftArguments);
 	readString(root, "type", out->type);
 
+	if(root.contains("assetIndex"))
+	{
+		out->mojangAssetIndex = assetIndexFromJson(requireObject(root, "assetIndex"));
+	}
 	readString(root, "assets", out->assets);
 
 	out->m_releaseTime = timeFromS3Time(root.value("releaseTime").toString(""));
@@ -67,14 +102,24 @@ VersionFilePtr MojangVersionFormat::versionFileFromJson(const QJsonDocument &doc
 		{
 			auto libObj = requireObject(libVal);
 
-			auto lib = OneSixVersionFormat::libraryFromJson(libObj, filename);
+			auto lib = MojangVersionFormat::libraryFromJson(libObj, filename);
 			out->addLibs.append(lib);
 		}
 	}
+	if(root.contains("downloads"))
+	{
+		auto downloadsObj = requireObject(root, "downloads");
+		for(auto iter = downloadsObj.begin(); iter != downloadsObj.end(); iter++)
+		{
+			auto classifier = iter.key();
+			auto classifierObj = requireObject(iter.value());
+			out->mojangDownloads[classifier] = downloadInfoFromJson(classifierObj);
+		}
+	}
 	return out;
 }
 
-static QJsonDocument versionFileToJson(VersionFilePtr patch)
+QJsonDocument MojangVersionFormat::versionFileToJson(VersionFilePtr patch)
 {
 	QJsonObject root;
 	writeString(root, "id", patch->id);
@@ -95,10 +140,23 @@ static QJsonDocument versionFileToJson(VersionFilePtr patch)
 		QJsonArray array;
 		for (auto value: patch->addLibs)
 		{
-			array.append(OneSixVersionFormat::libraryToJson(value.get()));
+			array.append(MojangVersionFormat::libraryToJson(value.get()));
 		}
 		root.insert("libraries", array);
 	}
+	if(patch->mojangAssetIndex && patch->mojangAssetIndex->sizeAndHashKnown())
+	{
+		root.insert("assetIndex", MojangVersionFormat::assetIndexToJson(patch->mojangAssetIndex));
+	}
+	if(patch->mojangDownloads.size())
+	{
+		QJsonObject downloadsOut;
+		for(auto iter = patch->mojangDownloads.begin(); iter != patch->mojangDownloads.end(); iter++)
+		{
+			downloadsOut.insert(iter.key(), downloadInfoToJson(iter.value()));
+		}
+		root.insert("downloads", downloadsOut);
+	}
 	// write the contents to a json document.
 	{
 		QJsonDocument out;
@@ -133,3 +191,244 @@ QJsonDocument MojangVersionFormat::profilePatchToJson(const ProfilePatchPtr &pat
 	}
 	throw VersionIncomplete(QObject::tr("Unhandled object type while processing %1").arg(patch->getPatchName()));
 }
+
+/*
+class MojangDownloadInfo
+{
+	friend class MojangVersionFormat;
+public:
+	QString getUrl()
+	{
+		return m_url;
+	}
+
+	QString getSha1()
+	{
+		return m_sha1;
+	}
+
+	int getSize()
+	{
+		return m_size;
+	}
+
+protected:
+	QString m_url;
+	QString m_sha1;
+	int m_size;
+};
+*/
+
+MojangDownloadInfoPtr MojangVersionFormat::downloadInfoFromJson(const QJsonObject &obj)
+{
+	auto out = std::make_shared<MojangDownloadInfo>();
+	// optional, not used
+	readString(obj, "path", out->m_path);
+	// required!
+	out->m_sha1 = requireString(obj, "sha1");
+	out->m_url = requireString(obj, "url");
+	out->m_size = requireInteger(obj, "size");
+	return out;
+}
+
+/*
+class MojangLibraryDownloadInfo
+{
+	friend class MojangVersionFormat;
+public:
+	MojangDownloadInfo getDownloadInfo(QString classifier)
+	{
+		if (classifier.isNull())
+		{
+			return artifact;
+		}
+		
+		return classifiers[classifier];
+	}
+private:
+	MojangDownloadInfo artifact;
+	QMap<QString, MojangDownloadInfo> classifiers;
+};
+*/
+
+/*
+            "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"
+                    }
+                }
+            },
+*/
+
+
+MojangLibraryDownloadInfoPtr MojangVersionFormat::libDownloadInfoFromJson(const QJsonObject &libObj)
+{
+	auto out = std::make_shared<MojangLibraryDownloadInfo>();
+	auto dlObj = requireObject(libObj.value("downloads"));
+	if(dlObj.contains("artifact"))
+	{
+		out->artifact = downloadInfoFromJson(requireObject(dlObj, "artifact"));
+	}
+	if(dlObj.contains("classifiers"))
+	{
+		auto classifiersObj = requireObject(dlObj, "classifiers");
+		for(auto iter = classifiersObj.begin(); iter != classifiersObj.end(); iter++)
+		{
+			auto classifier = iter.key();
+			auto classifierObj = requireObject(iter.value());
+			out->classifiers[classifier] = downloadInfoFromJson(classifierObj);
+		}
+	}
+	return out;
+}
+
+LibraryPtr MojangVersionFormat::libraryFromJson(const QJsonObject &libObj, const QString &filename)
+{
+	LibraryPtr out(new Library());
+	if (!libObj.contains("name"))
+	{
+		throw JSONValidationError(filename + "contains a library that doesn't have a 'name' field");
+	}
+	out->m_name = libObj.value("name").toString();
+
+	readString(libObj, "url", out->m_base_url);
+	if (libObj.contains("extract"))
+	{
+		out->applyExcludes = true;
+		auto extractObj = requireObject(libObj.value("extract"));
+		for (auto excludeVal : requireArray(extractObj.value("exclude")))
+		{
+			out->extract_excludes.append(requireString(excludeVal));
+		}
+	}
+	if (libObj.contains("natives"))
+	{
+		QJsonObject nativesObj = requireObject(libObj.value("natives"));
+		for (auto it = nativesObj.begin(); it != nativesObj.end(); ++it)
+		{
+			if (!it.value().isString())
+			{
+				qWarning() << filename << "contains an invalid native (skipping)";
+			}
+			OpSys opSys = OpSys_fromString(it.key());
+			if (opSys != Os_Other)
+			{
+				out->m_native_classifiers[opSys] = it.value().toString();
+			}
+		}
+	}
+	if (libObj.contains("rules"))
+	{
+		out->applyRules = true;
+		out->m_rules = rulesFromJsonV4(libObj);
+	}
+	if (libObj.contains("downloads"))
+	{
+		out->m_mojang_downloads = libDownloadInfoFromJson(libObj);
+	}
+	return out;
+}
+
+QJsonObject MojangVersionFormat::downloadInfoToJson(MojangDownloadInfoPtr info)
+{
+	QJsonObject out;
+	if(!info->m_path.isNull())
+	{
+		out.insert("path", info->m_path);
+	}
+	out.insert("sha1", info->m_sha1);
+	out.insert("size", info->m_size);
+	out.insert("url", info->m_url);
+	return out;
+}
+
+QJsonObject MojangVersionFormat::libDownloadInfoToJson(MojangLibraryDownloadInfoPtr libinfo)
+{
+	QJsonObject out;
+	if(libinfo->artifact)
+	{
+		out.insert("artifact", downloadInfoToJson(libinfo->artifact));
+	}
+	if(libinfo->classifiers.size())
+	{
+		QJsonObject classifiersOut;
+		for(auto iter = libinfo->classifiers.begin(); iter != libinfo->classifiers.end(); iter++)
+		{
+			classifiersOut.insert(iter.key(), downloadInfoToJson(iter.value()));
+		}
+		out.insert("classifiers", classifiersOut);
+	}
+	return out;
+}
+
+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())
+	{
+		libRoot.insert("url", library->m_base_url);
+	}
+	if (library->isNative())
+	{
+		QJsonObject nativeList;
+		auto iter = library->m_native_classifiers.begin();
+		while (iter != library->m_native_classifiers.end())
+		{
+			nativeList.insert(OpSys_toString(iter.key()), iter.value());
+			iter++;
+		}
+		libRoot.insert("natives", nativeList);
+		if (library->extract_excludes.size())
+		{
+			QJsonArray excludes;
+			QJsonObject extract;
+			for (auto exclude : library->extract_excludes)
+			{
+				excludes.append(exclude);
+			}
+			extract.insert("exclude", excludes);
+			libRoot.insert("extract", extract);
+		}
+	}
+	if (library->m_rules.size())
+	{
+		QJsonArray allRules;
+		for (auto &rule : library->m_rules)
+		{
+			QJsonObject ruleObj = rule->toJson();
+			allRules.append(ruleObj);
+		}
+		libRoot.insert("rules", allRules);
+	}
+	if(library->m_mojang_downloads)
+	{
+		auto downloadsObj = libDownloadInfoToJson(library->m_mojang_downloads);
+		libRoot.insert("downloads", downloadsObj);
+	}
+	return libRoot;
+}
diff --git a/logic/minecraft/MojangVersionFormat.h b/logic/minecraft/MojangVersionFormat.h
index cd87d68e..67066647 100644
--- a/logic/minecraft/MojangVersionFormat.h
+++ b/logic/minecraft/MojangVersionFormat.h
@@ -1,6 +1,7 @@
 #pragma once
 
 #include <minecraft/VersionFile.h>
+#include <minecraft/Library.h>
 #include <QJsonDocument>
 
 #include "multimc_logic_export.h"
@@ -11,4 +12,18 @@ public:
 	// version files / profile patches
 	static VersionFilePtr versionFileFromJson(const QJsonDocument &doc, const QString &filename);
 	static QJsonDocument profilePatchToJson(const ProfilePatchPtr &patch);
+
+	// libraries
+	static LibraryPtr libraryFromJson(const QJsonObject &libObj, const QString &filename);
+	static QJsonObject libraryToJson(Library *library);
+
+private:
+	static QJsonDocument versionFileToJson(VersionFilePtr patch);
+
+	static MojangAssetIndexInfoPtr assetIndexFromJson (const QJsonObject &obj);
+	static MojangDownloadInfoPtr downloadInfoFromJson (const QJsonObject &obj);
+	static MojangLibraryDownloadInfoPtr libDownloadInfoFromJson (const QJsonObject &libObj);
+	static QJsonObject assetIndexToJson (MojangAssetIndexInfoPtr assetidxinfo);
+	static QJsonObject libDownloadInfoToJson (MojangLibraryDownloadInfoPtr libinfo);
+	static QJsonObject downloadInfoToJson (MojangDownloadInfoPtr info);
 };
diff --git a/logic/minecraft/ProfileUtils.cpp b/logic/minecraft/ProfileUtils.cpp
index 096f43bf..30e83a1f 100644
--- a/logic/minecraft/ProfileUtils.cpp
+++ b/logic/minecraft/ProfileUtils.cpp
@@ -153,9 +153,9 @@ VersionFilePtr parseBinaryJsonFile(const QFileInfo &fileInfo)
 
 void removeLwjglFromPatch(VersionFilePtr patch)
 {
-	auto filter = [](QList<RawLibraryPtr>& libs)
+	auto filter = [](QList<LibraryPtr>& libs)
 	{
-		QList<RawLibraryPtr> filteredLibs;
+		QList<LibraryPtr> filteredLibs;
 		for (auto lib : libs)
 		{
 			if (!g_VersionFilterData.lwjglWhitelist.contains(lib->artifactPrefix()))
diff --git a/logic/minecraft/ProfileUtils.h b/logic/minecraft/ProfileUtils.h
index 1e6d6a8f..267fd42b 100644
--- a/logic/minecraft/ProfileUtils.h
+++ b/logic/minecraft/ProfileUtils.h
@@ -1,5 +1,5 @@
 #pragma once
-#include "RawLibrary.h"
+#include "Library.h"
 #include "VersionFile.h"
 
 namespace ProfileUtils
diff --git a/logic/minecraft/OneSixRule.cpp b/logic/minecraft/Rule.cpp
similarity index 99%
rename from logic/minecraft/OneSixRule.cpp
rename to logic/minecraft/Rule.cpp
index 3f4a6bb9..c8ba297b 100644
--- a/logic/minecraft/OneSixRule.cpp
+++ b/logic/minecraft/Rule.cpp
@@ -16,7 +16,7 @@
 #include <QJsonObject>
 #include <QJsonArray>
 
-#include "OneSixRule.h"
+#include "Rule.h"
 
 RuleAction RuleAction_fromString(QString name)
 {
diff --git a/logic/minecraft/OneSixRule.h b/logic/minecraft/Rule.h
similarity index 90%
rename from logic/minecraft/OneSixRule.h
rename to logic/minecraft/Rule.h
index f564c3fe..c8bf6eaa 100644
--- a/logic/minecraft/OneSixRule.h
+++ b/logic/minecraft/Rule.h
@@ -21,7 +21,7 @@
 #include <memory>
 #include "OpSys.h"
 
-class RawLibrary;
+class Library;
 class Rule;
 
 enum RuleAction
@@ -37,7 +37,7 @@ class Rule
 {
 protected:
 	RuleAction m_result;
-	virtual bool applies(const RawLibrary *parent) = 0;
+	virtual bool applies(const Library *parent) = 0;
 
 public:
 	Rule(RuleAction result) : m_result(result)
@@ -45,7 +45,7 @@ public:
 	}
 	virtual ~Rule() {};
 	virtual QJsonObject toJson() = 0;
-	RuleAction apply(const RawLibrary *parent)
+	RuleAction apply(const Library *parent)
 	{
 		if (applies(parent))
 			return m_result;
@@ -63,7 +63,7 @@ private:
 	QString m_version_regexp;
 
 protected:
-	virtual bool applies(const RawLibrary *)
+	virtual bool applies(const Library *)
 	{
 		return (m_system == currentSystem);
 	}
@@ -84,7 +84,7 @@ public:
 class ImplicitRule : public Rule
 {
 protected:
-	virtual bool applies(const RawLibrary *)
+	virtual bool applies(const Library *)
 	{
 		return true;
 	}
diff --git a/logic/minecraft/VersionFile.cpp b/logic/minecraft/VersionFile.cpp
index 08f53a37..410f6659 100644
--- a/logic/minecraft/VersionFile.cpp
+++ b/logic/minecraft/VersionFile.cpp
@@ -4,7 +4,7 @@
 #include <QDebug>
 
 #include "minecraft/VersionFile.h"
-#include "minecraft/RawLibrary.h"
+#include "minecraft/Library.h"
 #include "minecraft/MinecraftProfile.h"
 #include "minecraft/JarMod.h"
 #include "ParseUtils.h"
@@ -12,7 +12,7 @@
 #include "VersionBuildError.h"
 #include <Version.h>
 
-int findLibraryByName(QList<RawLibraryPtr> haystack, const GradleSpecifier &needle)
+int findLibraryByName(QList<LibraryPtr> haystack, const GradleSpecifier &needle)
 {
 	int retval = -1;
 	for (int i = 0; i < haystack.size(); ++i)
@@ -112,10 +112,10 @@ void VersionFile::applyTo(MinecraftProfile *version)
 	version->traits.unite(traits);
 	if (shouldOverwriteLibs)
 	{
-		QList<RawLibraryPtr> libs;
+		QList<LibraryPtr> libs;
 		for (auto lib : overwriteLibs)
 		{
-			libs.append(RawLibrary::limitedCopy(lib));
+			libs.append(Library::limitedCopy(lib));
 		}
 		if (isMinecraftVersion())
 		{
@@ -130,14 +130,14 @@ void VersionFile::applyTo(MinecraftProfile *version)
 		// library not found? just add it.
 		if (index < 0)
 		{
-			version->libraries.append(RawLibrary::limitedCopy(addedLibrary));
+			version->libraries.append(Library::limitedCopy(addedLibrary));
 			continue;
 		}
 		auto existingLibrary = version->libraries.at(index);
 		// if we are higher it means we should update
 		if (Version(addedLibrary->version()) > Version(existingLibrary->version()))
 		{
-			auto library = RawLibrary::limitedCopy(addedLibrary);
+			auto library = Library::limitedCopy(addedLibrary);
 			version->libraries.replace(index, library);
 		}
 	}
diff --git a/logic/minecraft/VersionFile.h b/logic/minecraft/VersionFile.h
index 64bec731..5e722dbf 100644
--- a/logic/minecraft/VersionFile.h
+++ b/logic/minecraft/VersionFile.h
@@ -7,9 +7,9 @@
 
 #include <memory>
 #include "minecraft/OpSys.h"
-#include "minecraft/OneSixRule.h"
+#include "minecraft/Rule.h"
 #include "ProfilePatch.h"
-#include "RawLibrary.h"
+#include "Library.h"
 #include "JarMod.h"
 
 class MinecraftProfile;
@@ -169,16 +169,22 @@ public: /* data */
 
 	/// MultiMC: override list of libraries (replaces the previously assembled lists)
 	bool shouldOverwriteLibs = false;
-	QList<RawLibraryPtr> overwriteLibs;
+	QList<LibraryPtr> overwriteLibs;
 
 	/// Mojang: list of libraries to add to the version
-	QList<RawLibraryPtr> addLibs;
+	QList<LibraryPtr> addLibs;
 
 	/// MultiMC: list of attached traits of this version file - used to enable features
 	QSet<QString> traits;
 
 	/// MultiMC: list of jar mods added to this version
 	QList<JarmodPtr> jarMods;
+
+	// Mojang: list of 'downloads' - client jar, server jar, windows server exe, maybe more.
+	QMap <QString, MojangDownloadInfoPtr> mojangDownloads;
+
+	// Mojang: extended asset index download information
+	MojangAssetIndexInfoPtr mojangAssetIndex;
 };
 
 
diff --git a/logic/minecraft/ftb/FTBProfileStrategy.cpp b/logic/minecraft/ftb/FTBProfileStrategy.cpp
index c4bfa27b..a86cdee3 100644
--- a/logic/minecraft/ftb/FTBProfileStrategy.cpp
+++ b/logic/minecraft/ftb/FTBProfileStrategy.cpp
@@ -60,7 +60,7 @@ void FTBProfileStrategy::loadDefaultBuiltinPatches()
 			file->id.clear();
 			for(auto addLib: file->addLibs)
 			{
-				addLib->m_hint = "local";
+				addLib->setHint("local");
 				addLib->setStoragePrefix(nativeInstance->librariesPath().absolutePath());
 			}
 			file->fileId = "org.multimc.ftb.pack";
diff --git a/logic/minecraft/liteloader/LiteLoaderInstaller.cpp b/logic/minecraft/liteloader/LiteLoaderInstaller.cpp
index 81e51cd7..25297fa4 100644
--- a/logic/minecraft/liteloader/LiteLoaderInstaller.cpp
+++ b/logic/minecraft/liteloader/LiteLoaderInstaller.cpp
@@ -21,7 +21,7 @@
 #include <QDebug>
 
 #include "minecraft/MinecraftProfile.h"
-#include "minecraft/RawLibrary.h"
+#include "minecraft/Library.h"
 #include "minecraft/onesix/OneSixInstance.h"
 #include <minecraft/onesix/OneSixVersionFormat.h>
 #include "minecraft/liteloader/LiteLoaderVersionList.h"
@@ -50,14 +50,14 @@ bool LiteLoaderInstaller::add(OneSixInstance *to)
 
 	QJsonArray libraries;
 
-	for (auto rawLibrary : m_version->libraries)
+	for (auto Library : m_version->libraries)
 	{
-		libraries.append(OneSixVersionFormat::libraryToJson(rawLibrary.get()));
+		libraries.append(OneSixVersionFormat::libraryToJson(Library.get()));
 	}
 
 	// liteloader
 	{
-		RawLibrary liteloaderLib("com.mumfrey:liteloader:" + m_version->version);
+		Library liteloaderLib("com.mumfrey:liteloader:" + m_version->version);
 		liteloaderLib.setAbsoluteUrl(QString("http://dl.liteloader.com/versions/com/mumfrey/liteloader/%1/%2").arg(m_version->mcVersion, m_version->file));
 		QJsonObject llLibObj = OneSixVersionFormat::libraryToJson(&liteloaderLib);
 		libraries.append(llLibObj);
diff --git a/logic/minecraft/liteloader/LiteLoaderVersionList.h b/logic/minecraft/liteloader/LiteLoaderVersionList.h
index 43bb270d..1dba4b6a 100644
--- a/logic/minecraft/liteloader/LiteLoaderVersionList.h
+++ b/logic/minecraft/liteloader/LiteLoaderVersionList.h
@@ -23,7 +23,7 @@
 #include "BaseVersionList.h"
 #include "tasks/Task.h"
 #include "net/NetJob.h"
-#include <minecraft/RawLibrary.h>
+#include <minecraft/Library.h>
 
 #include "multimc_logic_export.h"
 
@@ -58,7 +58,7 @@ public:
 	int timestamp;
 	bool isLatest;
 	QString tweakClass;
-	QList<RawLibraryPtr> libraries;
+	QList<LibraryPtr> libraries;
 
 	// meta
 	QString defaultUrl;
diff --git a/logic/minecraft/onesix/OneSixUpdate.cpp b/logic/minecraft/onesix/OneSixUpdate.cpp
index 3fd66920..da3bd504 100644
--- a/logic/minecraft/onesix/OneSixUpdate.cpp
+++ b/logic/minecraft/onesix/OneSixUpdate.cpp
@@ -28,7 +28,7 @@
 #include "BaseInstance.h"
 #include "minecraft/MinecraftVersionList.h"
 #include "minecraft/MinecraftProfile.h"
-#include "minecraft/RawLibrary.h"
+#include "minecraft/Library.h"
 #include "minecraft/forge/ForgeMirrors.h"
 #include "net/URLConstants.h"
 #include "minecraft/AssetsUtils.h"
@@ -213,7 +213,7 @@ void OneSixUpdate::jarlibStart()
 
 	auto metacache = ENV.metacache();
 	QList<ForgeXzDownloadPtr> ForgeLibs;
-	QList<RawLibraryPtr> brokenLocalLibs;
+	QList<LibraryPtr> brokenLocalLibs;
 
 	for (auto lib : libs)
 	{
diff --git a/logic/minecraft/onesix/OneSixVersionFormat.cpp b/logic/minecraft/onesix/OneSixVersionFormat.cpp
index 45eef278..4ccf6e78 100644
--- a/logic/minecraft/onesix/OneSixVersionFormat.cpp
+++ b/logic/minecraft/onesix/OneSixVersionFormat.cpp
@@ -4,6 +4,7 @@
 #include "minecraft/ParseUtils.h"
 #include <minecraft/MinecraftVersion.h>
 #include <minecraft/VersionBuildError.h>
+#include <minecraft/MojangVersionFormat.h>
 
 using namespace Json;
 
@@ -24,99 +25,22 @@ static QString readStringRet(const QJsonObject &root, const QString &key)
 	return QString();
 }
 
-RawLibraryPtr OneSixVersionFormat::libraryFromJson(const QJsonObject &libObj, const QString &filename)
+LibraryPtr OneSixVersionFormat::libraryFromJson(const QJsonObject &libObj, const QString &filename)
 {
-	RawLibraryPtr out(new RawLibrary());
-	if (!libObj.contains("name"))
-	{
-		throw JSONValidationError(filename +
-								  "contains a library that doesn't have a 'name' field");
-	}
-	out->m_name = libObj.value("name").toString();
-
-	readString(libObj, "url", out->m_base_url);
+	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);
-	if (libObj.contains("extract"))
-	{
-		out->applyExcludes = true;
-		auto extractObj = requireObject(libObj.value("extract"));
-		for (auto excludeVal : requireArray(extractObj.value("exclude")))
-		{
-			out->extract_excludes.append(requireString(excludeVal));
-		}
-	}
-	if (libObj.contains("natives"))
-	{
-		QJsonObject nativesObj = requireObject(libObj.value("natives"));
-		for (auto it = nativesObj.begin(); it != nativesObj.end(); ++it)
-		{
-			if (!it.value().isString())
-			{
-				qWarning() << filename << "contains an invalid native (skipping)";
-			}
-			OpSys opSys = OpSys_fromString(it.key());
-			if (opSys != Os_Other)
-			{
-				out->m_native_classifiers[opSys] = it.value().toString();
-			}
-		}
-	}
-	if (libObj.contains("rules"))
-	{
-		out->applyRules = true;
-		out->m_rules = rulesFromJsonV4(libObj);
-	}
 	return out;
 }
 
-QJsonObject OneSixVersionFormat::libraryToJson(RawLibrary *library)
+QJsonObject OneSixVersionFormat::libraryToJson(Library *library)
 {
-	QJsonObject libRoot;
-	libRoot.insert("name", (QString)library->m_name);
+	QJsonObject libRoot = MojangVersionFormat::libraryToJson(library);
 	if (library->m_absolute_url.size())
 		libRoot.insert("MMC-absoluteUrl", library->m_absolute_url);
 	if (library->m_hint.size())
 		libRoot.insert("MMC-hint", library->m_hint);
-	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())
-	{
-		libRoot.insert("url", library->m_base_url);
-	}
-	if (library->isNative())
-	{
-		QJsonObject nativeList;
-		auto iter = library->m_native_classifiers.begin();
-		while (iter != library->m_native_classifiers.end())
-		{
-			nativeList.insert(OpSys_toString(iter.key()), iter.value());
-			iter++;
-		}
-		libRoot.insert("natives", nativeList);
-		if (library->extract_excludes.size())
-		{
-			QJsonArray excludes;
-			QJsonObject extract;
-			for (auto exclude : library->extract_excludes)
-			{
-				excludes.append(exclude);
-			}
-			extract.insert("exclude", excludes);
-			libRoot.insert("extract", extract);
-		}
-	}
-	if (library->m_rules.size())
-	{
-		QJsonArray allRules;
-		for (auto &rule : library->m_rules)
-		{
-			QJsonObject ruleObj = rule->toJson();
-			allRules.append(ruleObj);
-		}
-		libRoot.insert("rules", allRules);
-	}
 	return libRoot;
 }
 
@@ -253,7 +177,7 @@ VersionFilePtr OneSixVersionFormat::versionFileFromJson(const QJsonDocument &doc
 template <typename T>
 struct libraryConversion
 {
-	static QJsonObject convert(std::shared_ptr<RawLibrary> &value)
+	static QJsonObject convert(std::shared_ptr<Library> &value)
 	{
 		return OneSixVersionFormat::libraryToJson(value.get());
 	}
diff --git a/logic/minecraft/onesix/OneSixVersionFormat.h b/logic/minecraft/onesix/OneSixVersionFormat.h
index 9d16cced..45a961e4 100644
--- a/logic/minecraft/onesix/OneSixVersionFormat.h
+++ b/logic/minecraft/onesix/OneSixVersionFormat.h
@@ -2,7 +2,7 @@
 
 #include <minecraft/VersionFile.h>
 #include <minecraft/MinecraftProfile.h>
-#include <minecraft/RawLibrary.h>
+#include <minecraft/Library.h>
 #include <QJsonDocument>
 
 class OneSixVersionFormat
@@ -16,8 +16,8 @@ public:
 	static QJsonDocument profilePatchToJson(const ProfilePatchPtr &patch, bool saveOrder);
 
 	// libraries
-	static RawLibraryPtr libraryFromJson(const QJsonObject &libObj, const QString &filename);
-	static QJsonObject libraryToJson(RawLibrary *library);
+	static LibraryPtr libraryFromJson(const QJsonObject &libObj, const QString &filename);
+	static QJsonObject libraryToJson(Library *library);
 
 	// jar mods
 	static JarmodPtr jarModFromJson(const QJsonObject &libObj, const QString &filename, const QString &originalName);
diff --git a/tests/tst_MojangVersionFormat.cpp b/tests/tst_MojangVersionFormat.cpp
index 4c48fcdc..a9a3f977 100644
--- a/tests/tst_MojangVersionFormat.cpp
+++ b/tests/tst_MojangVersionFormat.cpp
@@ -34,21 +34,19 @@ slots:
 		QJsonDocument doc = readJson("tests/data/1.9-simple.json");
 		auto vfile = MojangVersionFormat::versionFileFromJson(doc, "1.9-simple.json");
 		auto doc2 = MojangVersionFormat::profilePatchToJson(vfile);
-		writeJson("beast.json", doc2);
+		writeJson("1.9-simple-passthorugh.json", doc2);
 		QCOMPARE(doc, doc2);
 	}
-	// not yet
-	/*
+
 	void test_Through()
 	{
 		
 		QJsonDocument doc = readJson("tests/data/1.9.json");
 		auto vfile = MojangVersionFormat::versionFileFromJson(doc, "1.9.json");
 		auto doc2 = MojangVersionFormat::profilePatchToJson(vfile);
+		writeJson("1.9-passthorugh.json", doc2);
 		QCOMPARE(doc, doc2);
 	}
-	*/
-
 };
 
 QTEST_GUILESS_MAIN(MojangVersionFormatTest)