At first I wasn't quite sure what I was looking at -- but wow, this project rocks!

Kaitai is like protobuf, but for binary formats. It's an incredibly clever way to not write n*m-many parsers for each language. You write a spec for your binary format and the Kaitai libraries in each language can then decode (and presumably encode) the payloads. Gif, wav, pdf, zip, fbx, your custom format, whatever.

This web IDE makes it easy to visualize and develop parser specs against actual data.

Absolutely brilliant ideas!