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Rekordbox USB checker.
Drop the stick and find out at home. It opens the rekordbox database that is actually on it, checks every track against the files that are actually there, and tells you what a CDJ will do with each one — the missing tracks, the missing grids, the missing cues, and the formats the booth’s player will not read.
Drop your USB stick
The whole stick, not a folder on it — the checker needs /PIONEER and /Contents together. Nothing is uploaded and there is no server behind this page.
What is actually on a stick
A CDJ browses the database, not the disk.
Three folders, and only one of them is the one a player reads.
This is the fact everything else follows from, and almost nobody is told it. When you plug a stick into a CDJ in rekordbox mode, the player does not look at the files. It opens /PIONEER/rekordbox/export.pdb — a database rekordbox wrote at export time — and everything you browse, search and load comes out of that.
Which means the two failures nobody expects are the same failure seen from opposite sides. A track in the database with no file on the disk is the exclamation mark: it is in your playlist, you press load, and nothing happens. A file on the disk with no row in the database — which is what dragging an MP3 onto an already-exported stick produces — is invisible everywhere you would look for it. Not skipped with a message. Not at the bottom of the list. Absent from the playlists, from search, from the artist and album browse. It is still reachable if you switch the player out of rekordbox mode and browse the raw folders, which is a thing you can do at home and not a thing you are going to do at 2am with a record running out.
Both are joins, not guesses, because the database carries the path of every audio file and the path of every analysis folder. That is why this page can name the tracks rather than tell you to go and look.
| Folder | What it holds | What happens without it |
|---|---|---|
| /PIONEER/rekordbox/ | export.pdb — every track, artist, album, key, tempo, colour and playlist. exportExt.pdb holds My Tags. | The player shows the stick as empty. This is what a copied stick looks like. |
| /PIONEER/USBANLZ/ | One folder per track: the beat grid, the waveform, memory cues, hot cues and — on newer exports — the phrase analysis. | The track loads and plays. No grid, so no sync and no quantize. No cues. A flat bar where the waveform goes. |
| /Contents/ | The audio, in a folder tree rekordbox builds by artist and album. | The track is listed and will not load — the exclamation mark. |
| /PIONEER/MYSETTING.DAT | Your player settings: jog feel, quantize, auto cue level, needle lock. | Every player you plug into keeps whatever the last DJ left it on. |
The three analysis files
A stick can be perfect and still look wrong
Not versions of each other — generations of player. This is why your waveform is blue.
Every analysed track gets its own folder under /PIONEER/USBANLZ/ holding up to three files, and each one was added when a new CDJ needed something the last format could not carry. They accumulate; they do not replace each other.
| File | Written for | What only it holds |
|---|---|---|
| ANLZ0000.DAT | CDJ-900 / CDJ-2000, 2009 | The beat grid, the monochrome waveform, memory cues and hot cues A–C. |
| ANLZ0000.EXT | CDJ-2000NXS2, 2016 | The colour waveform, hot cues D–H, cue names and colours, the variable-tempo grid, and the phrase analysis. |
| ANLZ0000.2EX | CDJ-3000, 2020 | The three-band waveform a CDJ-3000 draws. |
So a stick exported years ago, or one whose tracks were analysed by an old rekordbox and never re-analysed, has .DAT and nothing else. It plays flawlessly. It also draws a blue waveform on a machine that cost four thousand pounds, shows no phrase view, and loses every hot cue name and colour you set. Nothing anywhere tells you that before you are standing at the deck — which is the specific gap this page was built to close.
The phrase analysis is the odd one out and worth knowing about: rekordbox stores it obfuscated, exclusive-ORed with a short repeating key derived from the number of phrases in the track. Older versions wrote it in the clear. A reader has to work out which it is looking at, which is why so few things read it at all.
Format and filesystem
What each generation of CDJ will actually play.
A file the player cannot read is not skipped with a message. It is absent.
Pioneer’s format support has moved three times since 2009, and a booth is whatever the venue bought. FLAC and Apple Lossless arrived with the CDJ-2000NXS2 in 2016, and so did anything above 48 kHz. On a CDJ-2000nexus those files do not appear in the browse list — there is no warning, no greyed-out row, nothing.
| Generation | Models | Plays | Reads |
|---|---|---|---|
| CDJ-2000 / CDJ-900 · 2009 | CDJ-2000, CDJ-900 | MP3, AAC, WAV, AIFF — up to 24-bit 48.0 kHz | FAT16, FAT32, HFS+ |
| CDJ-2000nexus · 2012 | CDJ-2000nexus, CDJ-900nexus, XDJ-1000 | MP3, AAC, WAV, AIFF — up to 24-bit 48.0 kHz | FAT16, FAT32, HFS+ |
| CDJ-2000NXS2 · 2016 | CDJ-2000NXS2, XDJ-1000MK2, XDJ-RX2, XDJ-XZ | MP3, AAC, WAV, AIFF, FLAC, ALAC — up to 24-bit 96.0 kHz | FAT16, FAT32, HFS+ |
| CDJ-3000 · 2020 | CDJ-3000, XDJ-RX3 | MP3, AAC, WAV, AIFF, FLAC, ALAC — up to 24-bit 96.0 kHz | FAT16, FAT32, exFAT, HFS+ |
The filesystem column is the one to read twice. AlphaTheta’s own list of gear that reads exFAT — last updated March 2022 — is CDJ-3000, XDJ-RX3, XDJ-XZ and nothing else. Players released since read it too; the CDJ-2000NXS2s that are still in most booths do not. A Mac formats anything over 32 GB as exFAT unless you tell it otherwise, which is exactly how a stick that worked at home is not seen at all in a club. Nothing in the range reads NTFS. Format as FAT32 and it works everywhere; the 4 GB per-file limit is not something a DJ track will ever hit.
The table covers the four generations you actually meet in a booth. Anything newer than a CDJ-3000 is a superset of its row, so a stick that clears the CDJ-3000 line clears those too — which is why the checker reports against the oldest player that will take each file rather than the newest.
A browser is not permitted to know how a drive is formatted, so this page cannot check it and does not pretend to. It tells you the command instead. Everything else on this list — the formats, the sample rates, the bit depths, the 32-bit float WAVs that rekordbox analyses and no player will touch — it reads out of the file headers on the stick.
Frequently asked
Common questions
Why does my USB not show up on the CDJs?+
In order of how often it happens: the stick was copied rather than exported, so there is no /PIONEER folder and the players have no database to browse; the stick is formatted exFAT and the booth has anything older than a CDJ-3000; the export was interrupted, so the database exists but half the tracks are missing; or the drive itself has failed. This page checks the first and third from the stick itself, and tells you exactly how to check the second, which a browser is not allowed to see.
What is the difference between copying files to a USB and exporting from rekordbox?+
Copying puts audio files on a drive. Exporting writes a database — /PIONEER/rekordbox/export.pdb — that lists every track with its tempo, key, artwork and playlists, plus a folder of analysis files holding the beat grid, the waveform and your cue points. A player browses the database, not the disk. On a copied stick the tracks are still playable through the folder browse, and you lose the beat grid, sync, quantize, every cue, every playlist, and search. It is the single most common reason a gig goes wrong.
What format should I use for a DJ USB stick — FAT32 or exFAT?+
FAT32, unless you know for certain the booth is one of the three players that read exFAT: CDJ-3000, XDJ-RX3, XDJ-XZ. That is AlphaTheta's own list. A Mac formats anything over 32 GB as exFAT by default, which is how a stick that worked at home comes up as nothing at all in a club with CDJ-2000NXS2s. FAT32 has a 4 GB limit per file, which no DJ track has ever come close to. Nothing in the Pioneer range reads NTFS.
Why do some tracks show an exclamation mark on the CDJ?+
The database has a row for the track and the audio file is not where the database says it is. It happens when the export was interrupted, when the file was deleted after the export, or when the stick ran out of space partway through writing. The track is right there in your playlist and it will not load. This page finds those by comparing every database row against the files actually on the stick, and names them.
Why is my waveform blue instead of colour?+
Rekordbox writes up to three analysis files per track, and they are generations of player rather than versions of each other. ANLZ0000.DAT is the original: beat grid, blue waveform, plain cues. ANLZ0000.EXT was added for the CDJ-2000NXS2 and carries the colour waveform, hot cues D to H, cue names and colours, and the phrase analysis. ANLZ0000.2EX is the CDJ-3000's three-band waveform. A stick exported by an old version of rekordbox, or one whose tracks were analysed years ago and never re-analysed, has only the first — so it plays perfectly and looks like 2012. This page reports which of the three each track has.
Will a 32-bit float WAV play on a CDJ?+
No, and this is the one that catches producers out. Every CDJ spec sheet says 16 or 24 bit integer. A 32-bit float WAV bounced straight out of a DAW is a completely legal file, rekordbox analyses it happily on a laptop, and the player refuses it. Bounce to 24-bit before you export. The checker reads the WAV format tag and flags these.
Does this upload my music?+
No, and it does not upload the database either. Everything is read in this browser tab — there is no server behind the page and no request goes out while it runs. Open your browser's network panel and watch it stay empty. Only the first 64 kilobytes of each audio file is read at all, which is the header; the audio itself is never touched.
How many tracks can it handle?+
As many as are on the stick. It reads the database in one pass and then the analysis files one at a time, so a few thousand tracks takes tens of seconds rather than minutes, and the progress bar counts real files rather than guessing. Nothing is sampled and nothing is capped — a report that stopped at the first hundred and did not say so would be worse than no report.
Can it fix the problems it finds?+
No, and deliberately. This never writes to your stick. Everything it finds is fixed in rekordbox — re-analyse the tracks that have no grid, re-export the stick when files are missing, and reformat as FAT32 if that is the problem. Writing to a drive somebody is about to take to a gig is not a thing a web page should do.
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DJ terms on this page: USB prep · CDJ · Beatgrid · Memory cue · Hot cue · Relinking missing files · Full glossary