AAC to MP3, for the players that never learned.
A bare .aac file — from a cheap recorder, an Android app, a radio stream capture — is AAC audio without the MP4 wrapper that would make it an .m4a. Plenty of players reject the naked version even though they play M4A happily. Drop it here; it leaves as an MP3, converted on your device.
Add your files
Drag files here, or press the button. Any common audio works — and videos too: we take just the sound out of an MP4 or MOV. Your files stay on your device the whole time.
MP3 · M4A · WAV · FLAC · Ogg · Opus · MP4 · MOV — even old AMR and WMA files. You can also paste a file from the clipboard.
Pick the format you want
Not sure? MP3 is the safe answer — it plays on everything.
Advanced options — quality, mono/stereo, volume+
The defaults are good — you can skip this whole box.
Higher = better sound, bigger file.
Mono halves the size — fine for voice.
Your privacy — live proof, not a promise
- Files uploaded
- 0 bytes
- Processing
- Not started yet
- Your files
- Stay in this browser tab — gone when it closes
- Converter engine
- Not downloaded — only fetched if a format needs it
One download, and it isn’t your audio
Converting to MP3 or WAV needs no download at all. Less common formats use a built-in converter engine (32.5 MB) that comes from this site — not from some other company — downloads once, and is then saved in your browser. Your audio is never part of that download: the engine comes to your files, your files don’t go to it.
Don’t take our word for it: open your browser’s DevTools, watch the Network tab, then convert a file. You’ll see nothing carrying your audio — because this page has no upload feature at all. There is nowhere for your file to go.
Scope note, so this stays exact: the claim is about your files — they never leave this device. The site around it is not claim-free. It loads Vercel Analytics for aggregate page traffic, plus Google Analytics and Ads tags if you accept the consent prompt. Those measure page visits and store-link clicks. They never receive your audio, because nothing does. Full privacy policy.
Converted files are never stored by this page — they exist only in this tab until you download them.
Shrinking, not just converting?
If the point is a smaller file — an attachment cap, a full phone — the free audio compressor solves backwards from a target size and lets you A/B the quality before you commit.
Convert, then transcribe
Need the words, not the audio? The free audio to text tool transcribes the same files on your device — no conversion step needed for anything a browser can decode. Or capture something new with the free online voice recorder.
AAC, M4A and the confusion between them
AAC is the codec; M4A is a container that holds it. An .m4a file is AAC in an MP4 box with an index and metadata; a bare .aac file is usually a raw ADTS stream with neither. Software that looks for the box refuses the bare stream — which is why the same audio plays as .m4a and fails as .aac. Converting to MP3 ends the wrapper argument entirely.
Where bare .aac files come from
Voice recorder hardware and older Android recorder apps that write the encoder output straight to disk; stream rippers and radio capture tools; some CCTV and dashcam audio. If yours came from a recorder, it is probably speech — which converts to a small, clean MP3 at 64–96 kbps mono.
If the file refuses to decode
Most .aac files decode natively in the browser. The occasional exotic one — unusual profiles, broken ADTS headers — falls through to this page's built-in ffmpeg engine automatically, which is far more forgiving. Both paths run on your device; the page shows which one handled each file.
How the conversion works
The same four steps whatever you drop in — none of them involve a server. The free online audio converter hub explains the whole pipeline, the format chooser and the comparison with upload-based converters.
Your browser opens the file itself
Drop a file in, and your browser reads it with the same built-in player it uses to play sound on any website. Videos work too — we take just the sound out of an MP4 or MOV and leave the picture alone. At this point nothing has left your device, and nothing will.
Your device does the converting
For MP3 and WAV, a small converter runs right here in this tab. For less common formats — Opus, Ogg, FLAC, M4A, or old files like AMR and WMA — a bigger converter engine (ffmpeg, ~32 MB) downloads once from this site and then also runs on your device. Either way, the work happens on your computer or phone, not on a server.
Trim and tidy before converting
You can cut silence off the start and end, make the sound louder, and choose the quality — all before the file is converted, so it is only converted once. Hidden info inside the file (like when and where it was recorded) is removed automatically, because a file you are about to share should not quietly carry that.
Download straight from this tab
The finished file is built in this tab and handed to you as a normal download — one at a time, or a whole batch bundled into a single ZIP. Close the tab and everything in it is gone. There is no account and no cloud copy, because there is no cloud.
AAC to MP3 — questions, answered
Why does my .aac file play in some apps but not others?+
Because it is a raw AAC stream without the MP4 container most software expects. Apps that sniff the audio play it; apps that look for the container refuse. An MP3 has no such split personality — every player treats it the same.
Is AAC better quality than MP3? Am I downgrading?+
AAC is the more efficient codec, so at equal bitrates AAC usually sounds slightly better. Converting to MP3 at the same or a higher bitrate keeps the difference inaudible for speech. You are trading a sliver of efficiency for universal compatibility.
Can I batch-convert a recorder's folder of .aac files?+
Yes — select them all, drop them in one go, and download the results as a single ZIP. Conversion runs serially on your device; nothing in the folder is uploaded anywhere.
Is this audio converter really free, with no limits?+
Yes. No account, no daily limit, no file-size tier and no watermark. Your own device does the converting, so an extra file costs us nothing — there is simply nothing for us to charge for or to cap.
Is my audio uploaded anywhere?+
No. The file is opened and converted inside your browser, on your device. This feature has no upload button behind the scenes — there is nowhere for your audio to go. Want proof? Open your browser's DevTools, watch the Network tab while you convert, and you'll see nothing carrying your audio.
What is the maximum file size?+
We don't set one. The real limit is your device's memory, because the whole file is handled in this tab. Files over 2 GB are refused, and if a file looks heavy for your device, the page warns you before starting. A laptop handles multi-hour recordings; a phone prefers shorter ones.
Does it work offline?+
Converting to MP3 or WAV works offline once the page is open. Other formats (Opus, Ogg, FLAC, M4A) need the bigger converter engine, which downloads once (~32 MB) from this site — after that it's saved in your browser, so those conversions work without re-downloading too.
Can I convert video files to audio?+
Yes. Drop in an MP4, MOV or WebM video and you get just the sound out of it — that's the whole 'MP4 to MP3' trick. The video itself is never uploaded or changed; only its audio is read.
Why is there no 'paste a link' option?+
Because this tool is for your files, from your device. A link box would turn it into a tool for downloading other people's audio from around the web, which is not what it's for — and every link would send someone's listening history through a converter. Local files only, on purpose.
What does 'remove hidden info' actually remove?+
Details stored invisibly inside the file: title, artist, album art, the exact time it was recorded, which app or phone recorded it, and sometimes even GPS location. It's removed by default because a file you're about to share shouldn't quietly tell people all that. Turn the option off and the details are kept instead.
Other conversions
Files worth converting start as recordings.
BlackBox records your day straight to compact, transcribed, searchable files on your phone — nothing to convert afterwards. Free on iPhone and Android.