Library Health Check

No. There is no upload endpoint behind this page and no request is made when you drop a file — you can open the network panel and watch. The XML is read with the browser's own file reader, parsed in the tab, measured in the tab and rendered in the tab. Nothing is stored, nothing is logged, and reloading the page destroys the result. The comparison against our catalog works the other way round: the key and tempo distribution of our catalog travels to you with the page, and the comparison happens on your machine.

A track is playable when it has a tempo, a key, and at least one other track in your own collection that is a safe Camelot move away and within 6% on the pitch fader. That is deliberately the lowest bar a record has to clear to be mixable at all — not a judgement about whether it is any good. A track can be your favourite record in the world and still be a dead end, and that is a statement about the gap around it rather than about the track.

It is the default pitch range on a CDJ, so it is the window you actually have without reaching for the range button. Wider is possible — ±10% and ±16% are a button press away, and master tempo will hold the key while you do it — but a tool that assumed you would stretch every mix to its limit would flatter the answer. The window is stated on the page so you can read the numbers as what they are.

Up to around 120 MB of XML, which is roughly 60,000 tracks. Above that the browser's own XML parser is the limit rather than anything we control, and the page will tell you so instead of hanging. Everything below that is fast — the measurement itself takes well under a second even on a very large collection, because it sorts each key once and then binary-searches the tempo window rather than comparing every track to every other track.

Not yet — this reads Rekordbox XML only, because that is the format we already parse properly for library import and we would rather support one format correctly than four badly. If you are on Serato or Traktor, most DJ software can export or convert to Rekordbox XML, and that export will work here.

Two options, and the right one depends on the track. If it is a record you love, the fix is buying the bridge — the CSV export lists each dead end with how many tracks we hold that would follow it, so you know whether the material exists before you go looking. If it is a record you bought once and never played, the fix is deleting it: a collection you cannot navigate is worse than a smaller one you can.

No, and the tool is careful not to say so. A dead end means nothing else in your collection sits one safe move and one pitch range away from it. A 174 BPM drum and bass track in a collection of house records is a dead end in that collection and a completely normal record everywhere else. It is a map of your collection, not a review of your taste.