Features

Search and requests

Search covers tracks, albums, artists, and playlists from the connected music catalog. It understands more than exact titles: a query like “workout energy” or “chill sunday” is routed to genre and mood browsing rather than plain-text search.

Every request opens a window where you can set, per request:

Lossless, the two matching options and the peer options are offered while slskd is one of the sources.

These choices are stored on the request itself, so a retry weeks later still honours what you originally asked for.

The requests screen

Requests are grouped by album and playlist, with a sidebar of groups and a detail panel for the selected one. The list is ordered by most recent activity, so anything you just asked for, or that just changed, is at the top. Each row shows when it was requested and when it last moved. You can filter it by status or by download source. The track table shows where each track came from, with a link to its licence when it has one.

From here you can retry a failed track, retry a whole group, cancel anything in flight, delete a request, prioritise it, or pause it.

The download queue

Downloads are worked through album by album and playlist by playlist, in the order you asked, so albums finish one after another instead of five arriving half done. An album from Usenet or torrent downloads alongside, without holding the rest up.

• Jump the queue. Move any track, album, or playlist to the front from its actions menu. A badge shows it took effect. Retried tracks are prioritised automatically.
• Pause and resume. Pause an individual album or playlist, or the entire queue, from the toolbar. A paused album or playlist stays parked until you resume it, including across a restart. Pausing the whole queue lasts until you resume it or the container restarts.
• Restart recovery. If Synthseek restarts mid-queue, it rebuilds the queue from the database on boot and picks up where it left off. Paused work stays paused, and work already handed to Lidarr is left alone.

Verified imports

Synthseek checks what arrived before it goes into your library.

• The file’s tags are checked against what you asked for, and a file that does not match closely enough is refused.
• With an AcoustID key configured, the audio itself is fingerprinted and identified, so a file whose tags look right but whose audio is by a different artist is refused. An identification that comes back inconclusive does not block anything; only positive evidence against the file does.
• A file whose tags cannot be read at all is refused rather than waved through.

A refused file is not thrown away.

The review queue

Anything that failed verification waits in a review queue. For each held file you can see exactly why it was rejected, listen to it, and then approve or discard it. Approving queues it for import. Discarding removes the file and leaves the rejection on record.

Held files are kept for a configurable retention period, fourteen days by default.

Source quarantine

When a source repeatedly delivers the wrong thing, that exact source and file pairing is quarantined and excluded from future searches. Other files from the same peer stay eligible; quarantine is deliberately narrow. You can see which sources have been set aside and why, and lift a quarantine at any time.

Separately, and off by default, peers can be automatically banned after a configurable number of failed attempts.

Automatic retries

Anything Synthseek could not find can be watched. A background sweep searches for watched tracks again, spacing the attempts out the longer a track stays missing. A brand new release is retried sooner than something missing for months.

A failed track shows when its next attempt is due and how many there have been, and you can retry it at once.

A track that failed because of a problem on your own machine, a full disk or an unwritable folder, does not spend any of its retry budget. That is not something another peer can fix, so Synthseek keeps waiting for you rather than quietly giving up.

This is off by default.

Quality upgrades

Already have a song in poor quality? Ask for a better copy and Synthseek replaces it in place.

• The decision reads the actual files, not search result metadata, so a claimed bitrate cannot fool it.
• The old file is moved to a recycle bin rather than deleted, and the move is verified before anything else happens.
• If the replacement cannot be completed, the original is restored where possible. Otherwise it waits in the recycle bin with a Restore beside it.
• The recycle bin empties itself after a retention period, thirty days by default.

You can upgrade one track, a selection from your library in one action, or whatever is playing, from the player. Synthseek reports the outcome of each one.

Bring in music you already have

Drag your own files into Synthseek, including zip archives. Each track is identified, tagged, and filed into your library the same way a download would be. If a file matches something you had already requested, that request is closed out for you.

Uploads are streamed rather than buffered, so large archives work. Archive contents are validated before extraction.

Your library

A full library section to browse everything you have.

• Tracks is a table, with sorting, per-column filters, and a requested-at column.
• Albums, Artists, and Playlists are card grids with artwork.
• Faceted filtering across all views, with counts that respect the other active filters.
• Search, sorting, and smooth infinite scrolling.
• Views refresh on their own as downloads finish. No manual reload.
• Select several tracks at once to retry, upgrade, add them to a playlist, or add them to the queue. Select several albums to add them to the queue. In both views, administrators can also move the selection to another library path or delete its files.

Track status sorting follows the real download pipeline order rather than alphabetical order, so active work sorts above resolved work, which sorts above unresolved work.

Content detail

Click any artist, album, or playlist and a rich detail view opens in place, without losing your spot. Navigation stacks, so you can go from an artist to one of their albums to a related artist and back out again.

Each view pulls from several metadata sources at once and streams the sections in as they arrive:

• Artwork, a biography, and factual details.
• For an artist: a discography, top tracks, similar artists, and links to their presence elsewhere.
• For an album or playlist: a full tracklist with live per-track status.
• An overlay showing what you already have in your library.
• Actions to request anything you are missing, individually or in bulk.

When a metadata source is unavailable, Synthseek says so, and says how long it has been unavailable, rather than quietly showing you an incomplete page.

Playlists

Full playlist management inside your library.

• Create a playlist from tracks you already have.
• Rename and delete your own playlists.
• Add and remove tracks, several at a time.
• Request a playlist from the catalog and Synthseek downloads every track, preserving the original order.

Playlist import and export

• Import from JSPF, XSPF, and Exportify CSV. The flow is a dry run first, showing you exactly what matched and what did not, then a commit of the selection you approve.
• Export to JSPF, round-trippable back into Synthseek.
• Duplicate tracks within an imported playlist are collapsed, with a count of how many were skipped.

Sync to a media server

Any eligible playlist can be pushed to Plex, Navidrome, or Jellyfin, one at a time or all at once, from either the requests screen or your library. A background job keeps synced playlists named correctly and topped up with tracks they are missing.

Renames flow both ways. Rename in Synthseek and the server follows within seconds; rename on the server and Synthseek picks it up on the next pass.

Sync only adds tracks to the server’s copy. The one exception is a playlist kept in sync with its source: a track removed there is removed from the server’s copy too.

Play it in the web app

Synthseek plays your library itself. Press play on any track and a player docks at the bottom of the page, with a full screen view for the artwork. Your media keys and lock screen see what is playing, and the space bar pauses and resumes it.

The player can shrink into the top bar, or pop out into a small window that floats above your other applications. That window needs Chrome or Edge, and the option says so where it is unavailable.

An album, an artist or a playlist plays as a whole. You can also add to the queue instead of replacing it, a track or a selection at a time.

With autoplay on, the queue does not run out. The player adds the closest tracks your library has to what you chose, listed apart from your own picks. It is off until you turn it on, from the player’s settings. You can also start a radio from a track, an album or an artist.

Playback is the original file. With Plex, Navidrome or Jellyfin connected, a track Synthseek has no file for can play from that server instead. If your browser cannot decode a track’s format, Synthseek converts it on the fly, and scrubbing still works. On a slow connection you can ask for a converted stream yourself, at the bitrate you choose, from the player’s settings.

Volume is evened out between tracks, so a quiet song does not disappear after a loud one. Synthseek measures how loud each file is in the background, and a track it has not reached yet plays unchanged. An album played straight through keeps its own quiet and loud tracks. Turn it off, or add a fixed amount on top, from the player’s settings.

One track runs straight into the next. From the player’s settings you can blend them instead, when a track ends and when you skip, and choose how long the blend lasts. A song played from your own files that ends in silence blends before the silence. A stream converted on the fly keeps a short pause between tracks.

The player has an equalizer, with the usual presets, a preamp, and curves of your own that you can save by name. It shapes only the browser you set it in. Boosting a band lowers the overall volume to match. A compressor sits next to it, off until you turn it on, to narrow the gap between loud and quiet passages.

Your queue is kept for you, so a reload or another computer picks it up where you left off. It is the same queue your music apps use, so one you left on your phone is offered back in the browser.

Only one place plays at a time. Press play in a second tab, or on another computer, and the sound moves there rather than doubling. Devices lists the tabs you have open, so you can send the sound to one and bring it back.

The full screen view can show the lyrics, following the song where they come with timings. A .lrc file beside the song, or lyrics in its tags, come first.

The heart marks the same favourite your music app marks.

What you play can reach Last.fm and ListenBrainz. Connect either under Settings, then Listening & discovery. A track counts once you have heard half of it or four minutes of it, whichever comes first.

Most music apps scrobble on their own, so Synthseek sends nothing from them unless you tick that app under the service you connected.

Play it in a music app

Synthseek speaks the Subsonic API, so apps built for that ecosystem, Feishin, Symfonium, DSub and others, can browse and play your library directly, without a media server in between. Turn it on in Settings, then Apps & API keys. It is off until you do.

Each person creates their own credential and pastes it into their app with the address and their username. A credential is shown once and can be revoked at any time.

What the app does sticks. Favourites, playlists you create and reorder, what you played, and the queue you left behind are the same ones the web app shows. Deleting a playlist from a music app deletes only the playlist, never the music in it, and removing the tracks themselves stays in the web app.

An app that offers a radio or a mix from a track, an album or an artist gets one from your library.

Playback is original quality by default. If your app asks for a particular format or caps the bitrate, Synthseek converts on the fly and sends that instead, and it can be switched off in settings. A converted stream cannot be seeked mid-track.

Lyrics and loudness measurements reach music apps too, for the apps that use them.

One limit worth knowing. A track is offered once Synthseek has located its file, or when a connected media server holds it. Music you copied into the folder by hand appears once the library scan has found and recognised it, or once you match it yourself.

Discovery

A dedicated Discover page opens on what is trending, with genres to browse and an artist spotlight. It also ranks what is most represented in your library, and lists your recent requests.

Connect your listening history

• ListenBrainz provides discovery mixes: collaborative filtering recommendations, weekly exploration, weekly jams, and daily jams. Choose which mixes you want, name them, and optionally have Synthseek request their tracks automatically as they refresh. A mix can be kept as a single playlist that updates in place, rather than creating a new dated playlist every time.
• Last.fm surfaces your recent scrobbles and top tracks, with real artwork, and powers similar-artist recommendations across the application.

Discovery integrations are per user. Each member connects their own accounts and gets their own mixes.

Import your existing library

Connect a library source and bring your existing collection across.

From Spotify, browse your saved albums, saved tracks, and playlists in a table with bulk selection, pick what you want, and import it. From Plex, Navidrome, or Jellyfin, import your playlists the same way. Imported playlists can be kept in sync, so new additions on the source side flow through automatically.

A playlist from one of those servers can skip downloading the tracks Synthseek does not have yet. Those can play from the server instead.

Each member connects their own account and imports into their own library.

Multi-user

Synthseek is built for more than one person.

• Local accounts, or sign in with Plex.
• Import members straight from your Plex server.
• Three roles: admin, trusted, and user.
• Administrator-only settings are hidden from everyone else, not merely disabled.
• Requests are scoped to their owner and show who made them.
• Each member has their own profile, their own connected accounts, and their own language preference.
• Optionally require administrator approval before a plain member’s requests download anything.
• Optionally cap how many tracks each member requests and how much space their music takes.

Interface

• Modern and responsive, with a bottom navigation bar on phones.
• Three themes: Synthseek, Midnight, and Ocean.
• Four languages: English, Español, Deutsch, and Français.
• Live progress everywhere, driven by server-sent events rather than polling.
• A progress dock that follows long-running work such as playlist population, library imports, and media server sync.
• In-app update notifications when a newer version is published, with the patch notes for it.

AI assistants

Synthseek ships an MCP server, so an assistant such as Claude can search, request, organise, play, and report on your library in plain language. Its tools cover search, downloads, requests, playlists, library, listening history, the player, settings, and operations.

Every connection is scoped to one member. An assistant sees and acts on that member’s account and library only, shaped by their role.

See the AI Assistants page.

Operations

• A jobs section listing every background job relevant to your setup, with when each one runs next and a button to run it now.
• A log viewer with level filtering, auto-refresh, and export.
• A live health view for each connected service.
• A system status page listing what limits Synthseek right now, such as a folder it cannot use, and a notice at the top of Settings while anything is wrong.
• Notifications on Discord, ntfy or Telegram, plus a webhook or Apprise for administrators, with each member picking what they receive.
• Automatic database backups before any schema change, and, where there is room, a copy-validated upgrade that proves the migration on a copy before touching your live database.