Game files

Game

All available version of the game itself are listed on

 http://s3.amazonaws.com/Minecraft.Download/versions/versions.json

The jar file for a specific version is located at

 http://s3.amazonaws.com/Minecraft.Download/versions/<version>/<version>.jar

Some information on how to properly run said jar is available at

 http://s3.amazonaws.com/Minecraft.Download/versions/<version>/<version>.json

Libraries

The libraries which can be used for all minecraft versions and are downloaded by the launcher are located at

 http://s3.amazonaws.com/MinecraftDownload/

The json file downloaded above is used in order to determine which libraries to download. Inside the file is a key, libraries which contains information about each library required. Example:

{
  "name": "org.lwjgl.lwjgl:lwjgl-platform:2.9.1-nightly-20130708-debug3",
  "natives": {
    "linux": "natives-linux",
    "windows": "natives-windows",
    "osx": "natives-osx"
  },
  "extract": {
    "exclude": [
      "META-INF/"
    ]
  },
  "rules": [
    {
      "action": "allow",
      "os": {
        "name": "osx",
        "version": "^10\\.5\\.\\d$"
      }
    }
  ]
}

The name key is used to determine the url from which to download the library from. The format of this string is <package>:<name>:<version> and can be turned into a path by replacing the periods in the package name with forward slashes and formatting a string with the template: <package>/<name>/<version>/<name>-<version>.jar.

The natives key provides a string for each specific platform to be inserted between the .jar and the <version> of the filename, resulting in a filename with the format: <name>-<version>-<native-string>.jar. This is applied to any file with the natives key.

The extract key provides rules for the extraction of the file.

The rules key is used to determine which platforms to download the file to. When the action is allow, the file will be downloaded to the platform stated in os. When the action is disallow, the file will not be downloaded to the platform stated in os. If there is no os key, the rule is default for non-specified platforms.

Assets

The game itself downloads further resources from

 http://s3.amazonaws.com/MinecraftResources/

A list of all available resources is available as an XML file at the address above. These files do not have to be downloaded in order for the game to function properly.