AcrossDownJS is a parser / conversion library that tackles the AcrossLite crosswords format. Its primary objective is to provide a trim, dependency-free tool to manipulate puz files both in the browser and via NodeJS; as such, it only uses language features with good browser support. This is also a documentation effort to try and determine what the AcrossLite specification is, since complete information on it is rather hard to find online.
The specification living-document can be found here.
Know a lot about crossword binary formats? Interested in staring longingly at bytes to try and guess what they mean? Open a PR! Any help is welcome on both the library and specification side of things.