HeroWO's HoMM 3 Map Processor

Produced by the HeroWO.js project - a JavaScript re-implementation of Heroes of Might and Magic III.

h3m2json.php

Parses .h3m files into various formats (uncompressed .h3m, JSON, PHP serialize()).
Compiles those formats back into .h3m. Can convert between different game versions.
Performs excessive error-checking (lots of potential warnings).
Provides ample debug information (byte-by-byte stream analysis, relation to parsed structures).
Built around an extensible architecture with current support of all official HoMM 3 versions (RoE, AB, SoD).
...and HotA, but keeps raw values for non-official content (e.g. numeric identifiers for HotA-specific terrain).
Written in an easy-to-follow manner. No C, please!
Can be called from CLI or include'd into your own script.

Run php h3m2json.php -h for details.

Documents the entire .h3m binary file format based on multiple sources, primarily on homm3tools.