An MP4 tagging library where all tags can be accessed and modified and any tags, unknown tags or custom tags are never lost when the audio file is updated. A list of known tags is only used when new tags are added.
mtag is the command-line tool for media files tagging. It can use the text file template to tag the multiply sets of media files. You can apply the same template for Ogg, MP3, and FLAC album versions.
adx is a minimalistic but full-featured address book. For contact management running completely in your web browser. Based on Plain Old XML (POX). FEATURES: Small (<350KB), lightweight, portable, contact tagging, geo mapping, web accounts, vCard download, QR code generator (offline) for (vCard, WiFi, free text), etc. HOW IT WORKS: Plain Old XML + XSLT = HTML web app in your web browser. Can be hosted online or local (disk, USB flash drive, etc). Own your data!
Picard is a cross-platform music tagger written in Python. It supports all common audio formats (MP3, FLAC, OGG, M4A, WMA). And uses AcoustID audio fingerprints, for automatic music identification; or look up CD images even. For additional features, a wide list of plugins is available; and it's easy to extend.