Free Online Audio Converter — AAC, MP3, WAV, FLAC, OGG
100% Private · Files never leave your browser
Convert audio between formats — right in your browser
Powered by ffmpeg.wasm (the same engine used by pros), this converter runs entirely on your device using WebAssembly. No upload, no signup, no size limit. Choose an output format, click Convert, and download. Your file never touches a server.
Why this is different from cloud converters: most "free online converters" upload your audio to a remote server, log what you converted, then maybe sell the data or show you ads. This one runs FFmpeg inside your browser tab. Close the tab and your file is gone — we never saw it.
How it works
The converter
Don't have a file? Try a sample.
These three clips are from SoundHelix (royalty-free, ~30 seconds, ~1 MB each). Click to load the sample into the converter — no upload happens. Note: if the sample doesn't load (some networks block third-party CDNs), use the Browse button above to pick a file from your device.
Why this converter is different
Popular conversions
| From | To | Why |
|---|---|---|
| M4A / AAC | MP3 | Older car stereos that don't play AAC |
| MP3 | WAV | Archive an edit before re-encoding |
| FLAC | MP3 | Lossless master → portable listening copy |
| WAV | OGG | Smaller files for podcasts / web embeds |
| AAC | FLAC | Preserve quality before further editing |
A note on Loopback Audio
This converter pairs perfectly with our $39 Loopback Audio device — which records Spotify, Apple Music, YouTube Music (and any audio playing on your phone or computer) directly to a TF card as AAC files. Use this tool to convert those recordings to MP3 if your car stereo only plays MP3.
Troubleshooting
The page is stuck on "Loading engine..." — The FFmpeg core is ~30 MB; on slow connections this can take 30–60 seconds. Watch the progress bar; if it's moving, it's working. If it stalls at zero, your network may be blocking esm.sh or jsdelivr — try refreshing.
"Could not load FFmpeg core from any CDN" — Your network or browser may be blocking external CDNs. Try a different network (mobile hotspot), or try a different browser. The tool is fully client-side, so a VPN or corporate firewall that blocks the CDNs will block the engine from loading.
"FFmpeg could not decode this file" — Your file uses a codec that browser-side FFmpeg can't handle. Common offenders: ALAC (.m4a from old iTunes), WMA, MIDI, ATRAC. Try converting with a desktop tool first, or use a different input file.
"Out of memory" — Your file is too large for your device's available RAM. Try a file under ~500 MB, or close other tabs.
Drag-and-drop doesn't work on mobile — Tap the "Browse for a file" button below the dropzone. iOS Safari and some Android browsers don't support file drag.
FAQ
Does my audio file get uploaded anywhere?
No. The file is loaded into your browser's memory via JavaScript's File API and processed by FFmpeg running inside a WebAssembly sandbox. It is never sent over the network. You can verify by opening DevTools → Network and watching — only the FFmpeg core + WASM binary are downloaded, never your file.
Why does the first conversion take longer?
The first conversion downloads the FFmpeg core (~30 MB compressed) from CDN. Your browser caches it, so subsequent conversions start instantly. After the first run, the page works offline too.
What's the largest file I can convert?
There is no software-side limit. The practical limit is your device's available RAM — modern browsers can typically handle 500 MB to 2 GB depending on your machine. Conversions of 1-hour audiobooks routinely complete in under a minute on a recent MacBook.
Which formats can I convert to?
MP3 (VBR via LAME), AAC/M4A (CBR, 128–320 kbps), WAV (16-bit PCM), FLAC (lossless), and OGG (Vorbis). Source formats include MP3, AAC, M4A, FLAC, OGG, WAV, OPUS — basically anything FFmpeg can decode.
Why use this instead of Audacity or VLC?
Audacity and VLC are excellent — and you should keep using them for editing. This tool is built for the 80% case where you just need to convert a file. There's nothing to install, no interface to learn, and no updates — it just works in your browser.
Does this work offline?
Yes, after the first page load. The FFmpeg core binary gets cached. If you go offline and reload the page (or revisit it later), the engine is still in your browser cache and works without internet.
What about DRM-protected files (Spotify Premium downloads, Apple Music, etc.)?
This tool converts files you already have. It can't bypass DRM. If a streaming service gives you a file, FFmpeg will only be able to convert it if the file is in an open format like MP3, AAC, FLAC, OGG, or WAV.
Is this converter really free?
Yes. The tool is part of Loopback Audio's site; we built it for our customers who need to reformat recordings. There is no premium tier, no signup, no ad, and we don't even run analytics on this page.
