My own little music player — a place to keep the songs I love and stream them from anywhere, without a subscription.

git clone https://github.com/kato/cassette
cd cassette
bun install

Create a .env file in the project root:

# MongoDB Atlas — holds the library (tracks, playlists, albums)
MONGO_URL="mongodb+srv://user:pass@cluster/cassette"

# Cloudflare R2 — stores the audio files
R2_ACCESS_KEY_ID="..."
R2_SECRET_ACCESS_KEY="..."
R2_BUCKET_NAME="cassette"
R2_PUBLIC_URL="https://media.example.com"   # public base URL for the bucket
R2_ACCOUNT_ID="..."                          # account id… or set R2_ENDPOINT below
# R2_ENDPOINT="https://<account>.r2.cloudflarestorage.com"

# Optional — gate the whole app behind one password (leave unset to keep it open)
AUTH_PASSWORD="change-me"

# Optional — pull tracks in by URL from an external importer service
MUSIC_IMPORTER_URL="https://importer.example.com"
IMPORTER_API_KEY="..."

New to R2? The key, secret, and endpoint all come from an S3-compatible API token on your bucket — Cloudflare's R2 S3 API guide walks through it.

Push the database schema:

bun run db:push

Add audio files (.mp3, .m4a, .flac, .ogg, .wav) to a top-level tracks/ folder (git ignored). One easy way to grab a song is yt-dlp:

yt-dlp -x --audio-format mp3 --embed-thumbnail -o "tracks/%(title)s.%(ext)s" "<url>"

Then ingest them — this uploads each file to R2, reads its metadata and artwork, and asks (right in the terminal) whether to drop the new tracks into the library or a playlist:

bun run ingest

Already have audio sitting in your bucket? Register anything not yet in the database:

bun run sync

Finally, start the dev server:

bun run dev

You can browse the database contents with Prisma Studio:

bun run db:studio

Open http://localhost:3000 to see the app.

I wanted this to run for free, basically forever, on someone else's hardware:

• MongoDB Atlas holds the library. Its free tier is generous enough that a personal collection never comes close to the limit.
• Cloudflare R2 stores the audio. The free tier has plenty of storage and — the part that matters — zero egress fees, so streaming my music doesn't quietly run up a bill.
• coss.com/ui for the components, so the interface stays consistent without hand-rolling every button and dialog.
• TanStack Virtual virtualizes the track table, so the library scrolls smoothly whether it holds 50 songs or 5,000.

Listening. Your whole collection lives in one virtualized table that stays smooth from 50 tracks to 5,000. Click a song to play, scrub the progress bar to seek, and the now-playing bar follows you everywhere. Favorites are one tap away in their own view.

Organizing. Group songs into playlists and albums, reorder them by dragging, and hide the albums you'd rather not see.

Getting music in. Drop files into tracks/ and bun run ingest uploads and tags them; bun run sync adopts anything already in your bucket. There's also an optional URL importer for pulling tracks in from elsewhere.

Keeping it yours. Set AUTH_PASSWORD and the whole app sits behind a single password — leave it unset and it stays open. Works the same on a phone as on a desktop.

MIT — do whatever you like with it.