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Unreal Package Lib

A small Java library for reading Unreal Engine packages.

Unreal Packages, are used by Unreal Engine games for packaging content such as maps, textures, sounds, and the gameplay code itself.

Although the files all have different file extensions for organisation purposes only (for example, .unr, .ut3, or .ut2 for maps, .utx for textures, .u for code), they all have the same structure and are capable of holding the same content.

This implementation supports at Unreal Engines 1, 2 and 3, has been tested using content and assets from Unreal, Unreal Tournament, Unreal Tournament 2004, and Unreal Tournament 3. Your mileage may vary with other games using these engines, especially Unreal Engine 3 variations.

Also provided via the Umod class is the ability to read and extract the contents of .umod installers, commonly used to distribute larger Unreal and Unreal Tournament modifications.

Finally, reading of Unreal Engine's .int files is provided via the IntFile class, which simplifies processing some of the non-INI file like properties contained within these files.

Current Implementation

  • Light-weight memory efficient implementation.
  • Reading all a packages' exported objects and their properties.
  • Read and export textures from most supported UE1 and UE2 formats.
  • Read and export sounds in WAV format.
  • Use UMOD package contents in combination with the package reader, to allow inspecting and exporting objects without needing to extract the UMOD contents.
  • Extendable with more object readers if needed (meshes, sounds, etc).
  • There is currently no support for reading or extraction of data such as UnrealScript classes.


Simple usage example, to read the title of a UT99 map, and save its screenshot.

There's a lot of boilerplate here, which could be hidden behind some utilities within your own implementation.

// load the package from file
Package pkg = new Package(Path.get("DM-MyLevel.unr"));

// get the LevelInfo object, which contains the properties we're looking for 
ExportedObject levelInfo = pkg.objectsByClassName("LevelInfo").iterator().next();
Object level = levelInfo.object();

// read the map title
String title = ((StringProperty)"Title")).value;

// get a Texture object from the Screenshot property
Property shotProp ="Screenshot");
ExportedObject shotObject = pkg.objectByRef(((ObjectProperty)shotProp).value);
Texture shot = (Texture)shotObject.object();

// get and save the screenshot from the first mipmap (the full size texture) to file
Texture.MipMap[] mipMaps = shot.mipMaps();
ImageIO.write(mipMaps[0].get(), "png", Path.get("scheenshot.png").toFile());

In this example, we unpack/extract the contents of a UMOD file to disk:

Path dest = Paths.get("/path/to/unpack/to"); 
Umod umod = new Umod(Paths.get("path/to/file.umod"));

// create a small buffer for file transfer
ByteBuffer buffer = ByteBuffer.allocate(1024 * 8);

for (Umod.UmodFile f : umod.files) {
  // skip the umod's manifest (.ini, .ini) files
  if ("System\\Manifest")) continue;

  System.out.printf("Unpacking %s ",;
  Path out = dest.resolve(filePath(;

  // re-create the directory structure within the umod
  if (!Files.exists(out)) Files.createDirectories(out);

  out = out.resolve(fileName(;
  System.out.printf("to %s%n", out);

  try (FileChannel fileChannel =, 
       StandardOpenOption.WRITE, StandardOpenOption.CREATE, 
    SeekableByteChannel fileData = {

    // stream the file form the umod to disk
    while ( > 0) {;

// --- file name and path utility functions used during unpacking

private String fileName(String path) {
  String tmp = path.replaceAll("\\\\", "/");
  return tmp.substring(Math.max(0, tmp.lastIndexOf("/") + 1));

private String filePath(String path) {
  String tmp = path.replaceAll("\\\\", "/");
  return tmp.substring(0, Math.max(0, tmp.lastIndexOf("/")));

For further usage examples, including reading of a UMOD packages contents in combination with the Package reader, refer to the unit tests.


Building the project requires Gradle. From the project root directory, execute:

./gradlew build     # linux/macos
gradlew.bat build   # windows

After build completes, the .build/libs/ directory will include a .jar file suitable for inclusion in your project.

Binaries / Maven Repository

A Maven repository containing the latest builds is also available:

Repository URL:

  • Group: net.shrimpworks
  • Artefact: unreal-package-lib
  • Version: 1.+


A small Java library for reading and exporting the contents of Unreal Engine 1, 2, and 3 packages and UMOD files








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