Turn MP3 audio files into AU. It is converted in your browser, so the file never leaves your device.
Drop MP3 files here
or choose from your computer paste with Ctrl V
from Photos or Files
Ready · other file types work too0 bytes uploaded, ever
Drop MP3 files onto the box above, or click it to choose them. ToAny reads the file's contents to detect the type, so a wrong extension does not matter.
Press Convert. Open Options first if you want to change the defaults. The work happens in this tab.
Save the AU, or download everything as one ZIP if you converted several files.
The MP3 to AU converter is part of this page and runs inside your browser. Your audio files are never sent to ToAny or to anyone else.
Nothing has to travel to a server and back, so the conversion starts the moment you press Convert, even on a slow connection.
No sign-up, no email address and no watermark. Add several files and download them together as a ZIP.
MP3 is lossy, so editing or re-saving it repeatedly degrades the sound. AU is simple and is still read by Unix tools and Java. MP3 is at home in music and podcasts that must play anywhere; AU is the usual choice for simple uncompressed audio and Unix and Java sound clips. AU cannot bring back detail that MP3 compression already removed; it simply stores the result without further loss, in a larger file.
The defaults suit most files. Under Options you can trim the start and end.
This pair uses the compatibility engine, ffmpeg built for the browser, because AU cannot be written by the browser's built-in codecs. It is a one-off download of about 10 MB that the browser keeps, it is slower than the built-in codecs, and it takes files up to 1 GB.
MP3 is the audio format everything plays. It shrinks audio to roughly a tenth of its uncompressed size by discarding sound most listeners cannot hear. Newer codecs are more efficient, but nothing matches its compatibility.
Opens in Every phone, computer, car stereo and speaker
MP3 converterAU is one of the oldest audio containers: a short header followed by the samples. It comes from Sun workstations and NeXT, was the sound format of early web pages and Java, and often holds 8-bit μ-law telephone audio. Newer files can hold 16-bit PCM or floating point.
Opens in Audacity, VLC, QuickTime and most audio editors
AU converter| MP3MP3 audio | AUSun AU audio | |
|---|---|---|
| Stands for | MPEG-1 Audio Layer III | Sun/NeXT audio file (AU or SND) |
| Type | Audio | Audio |
| Compression | Lossy | Usually none |
| Introduced | 1993, by the Fraunhofer Society and the Moving Picture Experts Group | The late 1980s, by Sun Microsystems |
| Opens in | Every phone, computer, car stereo and speaker | Audacity, VLC, QuickTime and most audio editors |
| Best for | Music and podcasts that must play anywhere | Simple uncompressed audio and Unix and Java sound clips |
| File extension | .mp3 | .au, .snd |
No. The MP3 to AU conversion runs inside your browser, on your own phone or computer. The file is not sent to ToAny or to anyone else.
No further quality is lost: AU stores the decoded audio exactly. It cannot restore what MP3 compression already discarded, and the file will be larger.
Yes. Add as many as you like, convert them together and download each result or all of them as one ZIP.
The steps are the same everywhere because ToAny runs in the web browser: open this page in a current version of Chrome, Edge, Safari or Firefox, add the MP3 file, press Convert and save the AU. There is nothing to install.
Yes. MP3 to AU runs on the compatibility engine, which takes files up to 1 GB, and a long clip takes a while because it is slower than the browser's built-in codecs. Beyond that the limit is your device's memory, since nothing is uploaded; a computer copes with large files better than a phone.