Free AAC Converter: No Sign-up, Files Never Uploaded
Change the format of AAC files for free, with no sign-up and no upload. The conversion happens in this tab, so your files never leave your computer or phone.
AAC in short. Advanced Audio Coding: the successor to MP3 with better quality at the same bitrate. This is the raw AAC stream; the same audio inside an MP4 container is M4A.
From AAC you can convert to MP3, WAV, OGG, Opus, M4A and M4R, and 6 more formats. Some of these pairs can need a one-time engine download, which the page announces before it starts.
- Free
- No sign-up
- Never uploaded
- No watermark
Your files are converted on your device and never uploaded.
How to convert
- Add your AAC files by dragging them onto the converter or by using the file picker.
- Choose the format you want from the list of targets that fit your file.
- Open the options if you want to change quality or size, or keep the defaults.
- Press Convert and watch the progress shown for each file.
- Download each result, or take them all together as one ZIP when you converted several files.
Features
- Reads .aac files and can also write them.
- Free, with no watermark added to the result.
- No sign-up and no login.
- Your files are never uploaded and never leave your device.
- Batch conversion with a ZIP download for several results.
- The input is recognised by its content, not only by its file name.
- 12 target formats to choose from.
- A one-time engine download is cached by your browser.
Supported formats
| Format | Read | Write | Notes |
|---|---|---|---|
| MP3.mp3 | Yes | Yes | Lossy audio format that plays on practically every device. |
| WAV.wav | Yes | Yes | Usually uncompressed PCM audio, so files are large. |
| OGG.ogg | Yes | Yes | Container from the Xiph.Org Foundation, usually holding Vorbis or Opus audio. |
| Opus.opus | Yes | Yes | Open, royalty-free codec standardised by the IETF in 2012 (RFC 6716). |
| AAC.aac | Yes | Yes | Advanced Audio Coding: the successor to MP3 with better quality at the same bitrate. |
| M4A.m4a | Yes | Yes | Audio in an MP4 container, usually AAC and sometimes Apple Lossless. |
| M4R.m4r | Yes | Yes | iPhone ringtone: an M4A file with the .m4r extension. |
| FLAC.flac | Yes | Yes | Free Lossless Audio Codec: compresses audio without discarding anything. |
| ALAC.m4a | Yes | Yes | Apple Lossless: lossless compression stored in an M4A file. |
| WebM Audio.weba | Yes | Yes | Audio-only WebM file, normally holding Opus or Vorbis. |
| AIFF.aiff | Yes | Yes | Apple’s uncompressed PCM audio format, introduced in 1988. |
| WMA.wma | Yes | No | WMA encoding is not offered; open the file and convert it to MP3, WAV or another format. |
| AMR.amr | Yes | Yes | Adaptive Multi-Rate: a speech codec standardised by 3GPP for mobile phones. |
| AC3.ac3 | Yes | Yes | Dolby Digital: lossy surround-sound audio, up to 5.1 channels. |
| CAF.caf | Yes | No | CAF is read only here; convert it to WAV, FLAC or MP3. |
| AU.au | Yes | No | AU is a legacy format that is read only here; convert it to WAV or MP3. |
| MKA.mka | Yes | No | MKA is read only here; convert it to MP3, FLAC or WAV. |
| MP2.mp2 | Yes | No | MP2 is read only here; convert it to MP3 or WAV. |
| WebM.webm | Yes | Yes | Open, royalty-free format from Google, usually VP9 or AV1 video with Opus audio. |
About the formats
About AAC
Advanced Audio Coding: the successor to MP3 with better quality at the same bitrate.
This is the raw AAC stream; the same audio inside an MP4 container is M4A.
AAC uses lossy compression. It does not support transparency.
What AAC can become
AAC to MP3 runs in the page.
AAC to WAV runs in the page.
AAC to OGG runs in the page.
AAC to Opus runs in the page.
AAC to M4A runs in the page.
AAC to M4R runs in the page.
AAC to FLAC runs in the page.
AAC to ALAC can need a one-time download of about 31 MB.
Converting to AAC
Pages for converting to AAC start from MP3, WAV, FLAC and MP4.
Privacy: how it works
- Your AAC files stay on your device. The page reads each file with the browser's file API, converts it with code running in the tab, and hands the result back as a download. No upload happens, so there is no copy of your file on our servers to protect, delete or leak.
- There is nothing to sign up for and no login. The converter does not ask for an email address, and it does not need to know who you are to do its job.
- Some conversions use a WebAssembly engine that your browser downloads once, the first time you need it. Only the engine is fetched, never your file, and the page shows the approximate size before it starts. Your browser caches it, so later conversions skip the download.
- You can check the claim yourself: open your browser developer tools, watch the Network tab while a file converts, and you will see no request that carries your file.
Tips
- Keep your original recording. Encoding a lossy file again loses a little more quality each time.
- Choose a higher bitrate for music and a lower one for speech, where small files matter more than fine detail.
- Converting a lossy file to a lossless one only changes the container; it cannot bring back detail that is already gone.
- Convert one file first and listen before you start a long batch.
- AAC is lossy, so convert from the original when you can instead of from a copy.
Frequently asked questions
Is it really free?
Yes. There is no price, no trial, no credit card and no watermark added to your results. Ulkaa Tool does the conversion with your own device, so there is no server bill to pass on to you.
Are my files uploaded?
No. Your AAC files are read and converted inside your browser and are never sent to Ulkaa or to anyone else. The result is created on your device and you save it from there. Some conversions load a small conversion engine the first time you use them. That download is the only network traffic, it contains no file of yours, and your browser keeps it for next time.
Do I need an account?
No. There is no sign-up and no login. Open the page, add your files and convert. An Ulkaa account is not needed for anything on this tool.
Is there a file size limit?
No limit is set by us. The real limit is your device: the conversion uses your own memory and processor, so very large files can be slow or fail on a weak phone or an older computer. Close other heavy tabs and convert AAC files one at a time if a big batch struggles.
What can I convert AAC files to?
You can convert AAC to MP3, WAV, OGG, Opus, M4A, M4R, FLAC, ALAC, WEBA, AIFF, AC3 and AMR. Pick one on the converter and it applies to every file you add.
Can I convert other files to AAC?
Yes. MP3, WAV, FLAC and MP4 can be converted to AAC.
Can I convert many AAC files at once?
Yes. Add as many files as your device can handle. Each one is converted on its own and you can download them one by one or as a single ZIP.
Is AAC lossy?
Yes. AAC saves space by discarding some detail, so converting from AAC cannot restore what was lost and converting to it loses a little.