There are 2 repositories under fox-engine topic.
Fox Engine/MGSV/MGS dat, fpk, fpkd, pftxs and sbp unpacker/repacker
A community project to name every file used in Fox Engine game archives.
Fox Engine Texture (.ftex) to DDS converter
Fox Engine / MGS V: TPP file format research
Fox Engine XML compiler/decompiler
Fox Engine text and font converter