Playproof converts the tracks your gear can't play, repairs the files that fail for no obvious reason, and flags the FLACs that are secretly MP3s. It runs in your browser. Your music never leaves your machine.
The track is right there on the stick. The deck can see it. It just won't load it, and nothing tells you why.
Usually it's the WAV. A lot of them carry 32-bit float samples, or a
format tag called WAVE_FORMAT_EXTENSIBLE instead of plain
PCM. Bandcamp downloads do this. So do most DAW exports. No CDJ will
touch either one. Playproof rewrites the header and the file plays.
A CDJ-2000NXS plays MP3, AAC, WAV and AIFF. That's the whole list. If your library is FLAC or ALAC, none of it works, and plenty of clubs still run those decks.
Point Playproof at your folder and pick what you're playing on. It converts what needs converting and leaves the rest alone.
Someone converted a lossy file to FLAC. It's the right size, the right extension, and it sounds fine on laptop speakers. On a club system it doesn't.
Playproof looks at the spectrum of every track it touches. A lossy encoder throws away everything above a cutoff, and that cutoff survives being rewrapped. So the fake ones show up as a hard shelf where real music keeps going.
Most checkers judge a track against a fixed cutoff. That is why they flag so many ordinary records: an old recording or a dark master looks exactly like a transcode to a fixed rule.
Playproof measures each track against the rest of your library. If everything you own rolls off at 18 kHz, that's how you like your music and nothing gets flagged. If one track in a clean folder shelves at 16 kHz, that's the one worth listening to.
This needs a library to work. Scan a handful of tracks and there is nothing to compare against, so it falls back to judging each one on its own and says so rather than inventing a score.
Gear is grouped by what it can actually do, not by what it is called. An XDJ‑1000MK2 stops at 48 kHz and a CDJ‑3000 goes to 96, so they do not belong together no matter how similar the boxes look.
CDJ-3000X · CDJ-3000 · CDJ-2000NXS2 · CDJ-TOUR1 · OPUS-QUAD
FLAC and ALAC read natively. Almost nothing needs converting, so this is mostly a check that your files are what they claim.
XDJ-1000MK2 · XDJ-XZ · XDJ-RX3 · XDJ-AZ
A 96 kHz FLAC is refused here even though a CDJ-3000 plays it. ALAC is converted too — the 1000MK2 reads it, the XZ and RX3 do not.
CDJ-2000NXS · CDJ-2000 · CDJ-900NXS · CDJ-900 · CDJ-850 · CDJ-350 · XDJ-1000 · XDJ-700 · XDJ-RX2 · XDJ-RX · XDJ-RR · XDJ-R1 · XDJ-AERO
MP3, AAC, WAV and AIFF. That is the entire list. Lossless becomes AIFF, or 320 kbps MP3 if you would rather save the space.
SC6000 · SC6000M · SC5000 · SC5000M · PRIME 4+ · PRIME 4 · PRIME 2 · PRIME GO · SC LIVE 4 · SC LIVE 2
Reads more than anything else on the market, Ogg included. Almost a pure verification pass.
Factory head units · Pioneer, Kenwood, Sony, Alpine, JVC aftermarket
MP3 only, numbered filenames so tracks play in the order you meant, and one flat folder.
Hi-fi and AV receivers · smart TVs · boat stereos · portable players · PA and gym systems
The safest thing a stick can contain: 44.1 kHz MP3, short plain names, one folder. For gear whose manual is long gone.
Ceilings come from the manufacturers' published specifications, and the groupings are checked against them by the test suite — a wrong number here does not produce an error, it produces a stick your deck refuses.
Reads MP3, AAC, M4A, FLAC, ALAC, WAV, Ogg and Opus. Writes MP3, WAV and AIFF, carrying artist, title, album, artwork, BPM and key across — including into a WAV whose header it had to repair.
AIFF is the exception. Chrome has no AIFF decoder at all, so an AIFF library cannot be read there. Playproof writes AIFF perfectly well; it just cannot open one in the browser it otherwise recommends. Safari can, if that is what you have.
This isn't a promise, it's how the thing is built. Conversion happens in your browser using your own CPU. There's no server to send files to.
The app is allowed to contact exactly one address, and only when you enter a licence key. You can check that yourself: open developer tools and read the content security policy, or read the source, which is public.
Less than one month of a rekordbox subscription, paid once, for a tool you keep. No account, no expiry, nothing to renew.
Buying opens shortly — payment verification is still in progress. The free version is complete meanwhile.
Chrome, Edge or Brave to write straight to a USB stick, which is also what lets a second run skip the tracks it already did. Firefox and Safari can't give a website access to a folder, so there you get your library as ZIP files instead, split so no single download is unmanageable. You can choose the ZIP route in any browser if you would rather have an archive to copy over later.
No. It reads your music and writes converted copies to the folder you choose. Nothing in the source folder is touched.
It depends on your machine and on what you are converting to. AIFF and WAV are cheap — the work is decoding, then writing samples out again. MP3 is a great deal slower, because the encoder is genuinely computing something, and it is the one case where a big library means leaving it running. The app shows a live estimate once it has done enough tracks to have a basis for one, rather than guessing up front.
Files are written one at a time, as each finishes. If it is interrupted — you close the tab, the machine sleeps — everything already written stays written. Run it again into the same folder and it reads what is there and carries on. That last part needs a destination folder, so it does not apply to the ZIP route.
FAT32. Pioneer and AlphaTheta players read FAT16, FAT32 and HFS+, and not NTFS — a stick formatted by Windows' default can be invisible to the deck with nothing wrong with the files on it. FAT32 also cannot hold a single file over 4 GB, which Playproof accounts for.
Different job. OneLibrary carries cue points, beatgrids and playlists between recent gear from AlphaTheta, Native Instruments and Algoriddim. It doesn't convert audio. If your deck can't read FLAC, OneLibrary doesn't change that.
It might be wrong. A dark master or an old recording can look like a transcode to the analysis. Treat the list as tracks worth listening to rather than a verdict, and send the file over if you think the call is bad.
Yes. Paste it again. It doesn't expire and there's no device limit.
Free for 25 tracks. No account, no email address.
Open the app