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MP3 to AIFF.
Only for library consistency. It restores nothing. Some DJs keep a Rekordbox library in one format on purpose, because it makes behaviour predictable and stops a set list being a mix of containers. If that is you, this is the conversion — AIFF reads everywhere and tags properly.
Drop tracks to convert
WAV, AIFF, FLAC, MP3 or M4A. Drop a whole folder’s worth — one set of settings is applied to all of them and they come back as a single archive. Nothing is uploaded; the page makes no network request.
What it costs
A bigger file is not a better one.
The part every other converter leaves out, because it is the part that sometimes says don't.
About ten times the disk for identical audio. Everything the MP3 encoder discarded stays discarded; the AIFF is a faithful, expensive copy of a lossy file. It is a filing decision, not a quality one, and worth doing only if the consistency is genuinely worth the space to you.
AIFF is the format Rekordbox is happiest with: it analyses fast, it carries proper tags, and every CDJ in service reads it. It is the same audio as WAV in a different wrapper, so it costs nothing to prefer it.
The four that matter
What each format is for
Ogg and Opus are missing on purpose: no CDJ reads either, so neither belongs in a DJ's library.
| Format | Size, roughly | What it is for |
|---|---|---|
| WAV | 10 MB a minute | Uncompressed and universal. Opens in everything ever written. Poor at holding tags, which is the one reason to prefer AIFF. |
| AIFF | 10 MB a minute | The same audio as WAV in a container that tags properly. What Rekordbox is happiest with and what every CDJ in service reads. |
| FLAC | About two-thirds of WAV | Lossless compression — identical samples, a third less disk, and a checksum so the file can prove it years later. Read by Rekordbox and the CDJ-3000, but not by the CDJ-2000NXS2. |
| MP3 | About 2.4 MB a minute at 320 | Lossy, permanent, and universal. The right last step for a stick and the wrong middle step in any chain. |
The rule underneath all of it: lossless to lossless costs nothing and can be undone, lossless to lossy costs audio you cannot get back, and lossy to lossless costs disk and recovers nothing. Only the middle one is a real decision.
Frequently asked
Common questions
Is there any point converting MP3 to AIFF?+
One good reason and one bad one. The good one is consistency — a library that is all AIFF behaves the same way everywhere and tags reliably. The bad one is thinking it improves the audio, which it cannot: the file gets ten times bigger and sounds exactly the same, because it is exactly the same.
Will it play better on a CDJ?+
It will load a little faster and it will not sound different. Every CDJ in service reads MP3 perfectly well, so if the file already works there is nothing to gain from the swap beyond how tidy you want your library to be.
Is AIFF better than WAV for this?+
Yes, on tags. The audio is identical between them, and AIFF holds artist and title reliably where WAV loses them between programs. Given they are the same size, there is no reason to choose WAV unless something specifically demands it.
Do my files get uploaded anywhere?+
No, and that is the main reason to use this rather than a site that asks you to wait for an upload. The MP3 is decoded, re-written as AIFF and handed back entirely inside this browser tab — open the network panel and watch it stay empty. There is no server behind the page, which means an unreleased promo is safe to drop on it and nothing is sitting in somebody's bucket afterwards.
Can I convert a whole folder at once?+
Yes. Drop as many files as you like, set the format once, and the whole queue is converted with a report for each file — what it came from, what it went to, and how the size compares. The results come back as a single archive rather than as thirty separate downloads, which is what you want when the next step is dragging a folder into Rekordbox.
Do the tags come across?+
Yes. Artist, title, album, album artist, genre, year, track number, label, remixer, composer, BPM, key, ISRC, comment and the cover art are all read off the MP3 and written into the AIFF, so a converted folder arrives in Rekordbox named rather than as a wall of filenames. The one thing that does not travel is anything a DJ program keeps in its own private frames — Serato's cue points and beat grid live in an undocumented block that nothing outside Serato reads, and no converter can carry them.
Is there a file size limit?+
Up to 800 MB per file, which is about 75 minutes of 24-bit stereo audio — a full recorded set fits comfortably. Past that it is the browser's own decoder that gives up rather than the tool.
How does this tool make its FLAC and MP3 files?+
The lossless formats are written here, and verified: every test file was decoded again by an independent decoder and compared sample by sample against the original, with zero differences. On real records the FLAC comes out at about 67% of the uncompressed size, which sits between the standard encoder's default setting and its slowest one. MP3 uses the reference encoder that has been the answer to that problem for twenty-five years, because a homemade one would not make bigger files, it would make worse-sounding ones.
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MP3 to WAV · FLAC to AIFF · WAV to AIFF · M4A to AIFF · Every direction
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