What is a .OBB file?
OBB (Opaque Binary Blob) is an Android APK expansion file - extra assets (textures, audio, video) too big to fit in the APK, downloaded alongside a game or app. It is often a ZIP, sometimes an encrypted jobb image or a game-specific bundle.
- Did you know
- Google Play caps the base APK size, so large games ship the rest as one or two .obb expansion files (main and patch) stored under Android/obb on the device.
- Each OBB expansion file can be up to 2 GB, and an app may ship at most two of them: a main file and a smaller patch file.
- Google jobb tool can encrypt an OBB, but since August 2021 new large apps are steered towards Play Asset Delivery instead, making expansion files a legacy mechanism.
- What Analyser reads
- Identify and read more game and emulator files: Unity asset bundles, Unreal cooked assets, CISO/CHD disc images, FMOD/Wwise sound banks, Spine skeletons and atlases, GameMaker/LDtk/TIC-80 projects, Minecraft Anvil regions, Warcraft III maps, Ren Py and RPG Maker data, extra console ROMs (Atari, PC Engine, Master System/Game Gear, WonderSwan, 3DS homebrew), xdelta/Basis patches and emulator saves and movies.
- Depth of analysis
- .OBB is an identification-grade format: Analyser recognises it from its bytes and decodes the header metadata it carries, rather than opening it in a full viewer. Formats that do get a full viewer are marked "Full" on the formats page.
- Open a .OBB file
- Drag a .OBB file onto the Analyser home page (or tap to pick one). It is identified entirely in your browser - nothing is uploaded, there is no account, and it works offline once installed.