Xdelta is a neutral tool. However, you must own the original source file. Downloading commercial ROMs (e.g., a licensed Nintendo DS game) without owning the cartridge violates copyright law in most jurisdictions. Patching is legal when applied to your own dumped files.
If you’ve ever downloaded a "ROM hack" only to stare at a file you can’t open, or if you’re trying to squeeze a massive PS2 library onto a 64GB SD card, this is the tool you didn’t know you needed. Let’s dive into why patching on Android is a game-changer. xdelta patcher android