Slap ROM Patcher: Fast, Free, and Handles 20 Formats
Slap is a free, open-source ROM patcher that supports 20 formats and runs on multiple platforms. It was built for scripting, with structured errors and warnings, and it can apply, create, undo, convert, explain, and inspect patches. The author discusses the challenges of handling edge cases in various patch formats, such as IPS's 16MiB limit and BPS's out-of-order copying, and provides benchmarks showing Slap often outperforms reference tools.
It assumes nothing about a patch. I am fairly confident that it’ll handle anything that _isn’t invalid_ gracefully; if something is malformed, or coherent but about to do something surprising, slap says exactly what and where.