Slap ROM Patcher: Fast, Free, and Handles 20 Formats

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.
  1. matheusmoreira

    > nyuu.page

    Is this in any way related to byuu, the SNES emulator author?

  2. gblargg

    Doesn't the undo functionality cause it to store copyrighted data from the original ROM in the patch?

  3. yjftsjthsd-h

    > It is written in Haskell and Rust and this made getting it to work nicely in the browser, interesting

    I imagine. What motivated using that combination?

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2026-08-10