How enrichment works
When you play a track, Kapell surfaces its credits, samples, and history — drawn from open music data, with every fact carrying its source.
Overview
Enrichment is the part of Kapell that turns a bare track into a story — who produced it, who wrote it, who played on it, what it sampled, and the history around it. The player itself runs entirely on your Mac, against your Apple Music® library. Enrichment is the one piece that reaches out to a backend to look things up — and it only ever looks up music.
None of this is data Kapell invented. It’s the work of people who’ve spent two decades cataloguing who did what on millions of recordings. Our job is to bring it together cleanly, quickly, and with its sources intact.
The lookup, step by step
Each time a track starts, Kapell runs a short, ordered sequence. Nothing here describes you — only the recording.
The backend receives a track identifier. It never receives your name, your library, or what else you've played.
Where the facts come from
Every credit Kapell shows is traceable to a source, displayed inline next to the fact. These are the people doing the heavy lifting:
- MBMusicBrainz — credits and personnel (producers, writers, engineers, session players), plus sample and interpolation lineage. Data from MusicBrainz. musicbrainz.org · license
- WDWikidata — structured facts MusicBrainz lacks (birthplaces, awards, instruments) and the links that connect everything else. CC0. wikidata.org · licensing
- WPWikipedia — lead paragraphs and article sections (background, reception, personnel). Text is reused under CC BY-SA 4.0, with attribution to the named article and share-alike. wikipedia.org · reuse guide
- ABAcousticBrainz — acoustic descriptors like mood, genre, and timbre. CC0. acousticbrainz.org
- LBListenBrainz — popularity and similarity signals. CC0. listenbrainz.org
- RBReccoBeats — audio features like energy, tempo, and valence. reccobeats.com
What Kapell adds
The sources do the real work. Kapell’s contribution is the part in the middle, and we try to keep it modest and useful:
- 01It's unified. The backend joins about a dozen open sources into one response, keyed on the Apple IDs of your music and tied together through a shared open identifier.
- 02It's fast. Lookups are cached; warm ones come back in tens of milliseconds.
- 03It's current. Kapell tracks the upstreams as they update — MusicBrainz roughly twice weekly, Apple's catalog daily, others on their own cadence. (AcousticBrainz is the exception: it's been frozen since 2022.)
- 04It's cited and honest. Every fact carries its source. When a field has no data, it shows up empty — never silently dropped, never guessed at.
- 05Tie breakers and such. Occasionally there are places where our data sources don't get the right connections. Kapell contains a scant few tiebreakers and thumbs-on-the-scale to help the experience.
Over time we will fold in more sources and more capabilities as new data and methods prove out. We’d rather ship those quietly when they’re real than promise them here.
What enrichment costs you: nothing extra
Kapell is a one-time purchase, and enrichment is part of it — not a subscription, not an add-on, not a meter that starts after a trial. Buy Kapell once and the enrichment layer comes with it.
When you pay for Kapell you’re also paying for the maintenance of a beefy backend. To answer in tens of milliseconds, the API keeps about a dozen open datasets joined and held in memory — the whole graph in RAM, not a cold database we hit one query at a time. And the data is only worth having if it’s current, so we track the upstreams as they change — hourly, daily, and weekly for some — and fold the updates in for you.
It’s also ongoing work, not a finished thing. We’re always tuning how tracks match to the right credits, chasing down the gaps, and folding in better data and new sources as they prove out. Big steps forward ride along with the app’s own major updates, the way good Mac software has always charged — buy the upgrade when it’s worth it, or keep the version you own. No rent in between.
You’re not paying for the data. That’s open, and we cite it. You paid once for the player, and keeping the enrichment unified, fast, and fresh is simply part of what that buys.
Controlling enrichment
Enrichment is turned on or off in Preferences (⌘,, the standard macOS shortcut). With it off, Kapell stops reaching out to the backend and plays as a fully local player; the telemetry rack shows the current state either way.
If a lookup keeps coming back empty, that’s usually the data, not a bug — and often something you can fix. See When enrichment is empty (and how you can help).