Local, lossless metadata editing for MP3, FLAC, M4A, and Opus audio files.
Drop audio files onto the page, or paste a YouTube or SoundCloud link to save a track, playlist, or album.
Tagium is a React app powered by Cobalt's download API, and a custom metadata engine.
Cobalt runs as our own deployment on Fly and is used strictly as a proxy, it hands back raw audio, and your browser does the rest. Downloads are never stored.
The metadata engine reads and rewrites tags in the browser, one driver per format. It writes new tags in around the audio rather than re-encoding, so tag editing is always lossless.
More docs in docs/
Bun and Node 24 (see .node-version). Vite+ (vp) drives dev, build, lint, and test.
bun install
bun run dev # app + api routes together
bun run test # unit + server tests
bun run test:e2e # playwright
bun run typecheck
bun run lintURL imports need a Cobalt instance — point COBALT_API_URL at one, or run a local checkout
with bun run dev:cobalt. Share links stay off unless VITE_PUBLIC_SHARE_LINKS_ENABLED=true
and their Cloudflare bindings are present.
Deploys go through Cloudflare Workers Builds; bun run deploy:preview and
deploy:production exist for manual uploads.
AGPL-3.0-only.