MultiPatch vs ROM Patcher

MultiPatch is a free macOS application for applying and creating file patches. It applies BPS, IPS, UPS, PPF, XDelta, BSDiff, and RUP (Ninja2) patches, and creates BPS, IPS, PPF, XDelta, and BSDiff patches. To apply one, users can select a patch file or drag it onto the application window, then choose the target file and where to save the result. The application identifies the format from the patch file extension, so that extension must be correct. BPS creation offers Linear and Delta modes: Delta patches are usually smaller, but take longer and require more memory. Creating UPS and Ninja2 patches is not supported. The maker says patching is built into the application rather than handled by external tools. Version 2.0 requires macOS 10.9 or later; older releases are available for Mac OS X 10.4 through 10.8. A separate basic command-line version can apply or create patches for scripts or terminal use. The application is GPL-licensed, while the bundled patching libraries have their own licenses.

ROM Patcher is a free browser tool that applies patch files to a user's legally dumped game backup and produces a modified ROM. Common uses include fan translations, bug fixes and ROM hacks. It supports IPS, UPS, BPS, xdelta, APS, PPF and RUP formats, and the site includes a Pokémon-focused patching guide. No installation or account is needed. ROM and patch files are processed in the browser rather than uploaded, stored or transmitted by the service; the resulting ROM is generated there and offered as a local download. Patching runs in a Web Worker so the page does not freeze when handling large ROM files. The site does not provide ROMs, so users need to supply their own legally dumped backups. Verification differs by format: UPS checks source and result ROMs with CRC32, while BPS checks the source, target and patch. IPS is limited to files smaller than approximately 16 MB and has no built-in checksum, so using the wrong ROM can silently corrupt it. The patched output can be loaded in an emulator of the user's choice. The maker describes the rest of the site as an early, growing preview.