Submit portable freeware that you find here. It helps if you include information like description, extraction instruction, Unicode support, whether it writes to the registry, and so on.
IDTE (https://idteid3tagedito.sourceforge.io/) is yet another media file metadata editor with a portable version. I haven't seen it around TPFC so here goes.
https://idteid3tagedito.sourceforge.io/ author wrote:IDTE is a full featured tag editor for Windows which supports tagging of FLAC, APE, ID3V1.x/2.x, WMA, LYRICS, VORBIS Tags in audio files. It also supports the playback of 40+ various lossy and lossless music formats such as FLAC, ALAC, OGG, APE, MP3 etc. It can rename files based on the tag information, export tag information, create playlists, search for incomplete tags on Internet, fetch lyrics, fetch cover art, supports CUE sheet, can process multiple files at same time, allows batch file processing, supports SFX, visualizations and more...