When a music library is full of wrong tags, missing covers, and blank ratings, Tagr lets you fix the whole collection from any browser, on desktop or phone. Three roles divide the work on your own server. Admins mount a music folder, press scan, and get a searchable table of every track, with sortable and filterable columns, more than 40 editable fields, and room for custom tags. Taggers make the changes: edit fields inline, swap album art, and match one song or a whole selection against MusicBrainz, ticking which fields to overwrite. Mistakes are cheap, because every edit is stored in a persistent change history with a revert action, viewable per song or per folder. Rule-based smart playlists, such as every track with an empty comment, show what still needs attention. Listeners browse and play without edit rights, using the waveform player, a Recently played view, and optional ListenBrainz scrobbling that each person connects to their own account. Supported formats include MP3, FLAC, WAV, AAC, OGG, M4A, M4B, WMA, AIFF, and Opus, with changes written straight back into the files. Swipe-friendly panels, an installable PWA, and five interface languages make the phone a comfortable place to work. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. AGPL-3.0 licensed.