Turn the audio from a WebM recording into an MP3 for players, editors and transcription tools. Free with clearly published fair-use limits — no sign-up, no watermarks.
Drop your WebM file here
or click to browse — One file per media job — 100 MB / 10 minute limit
☁️ Server conversion — your file is uploaded securely (HTTPS), converted, and removed from temporary processing storage after the request finishes. Forced-crash leftovers are removed by recovery sweeps. A verified codec/duration report is included on the download page. Which tools upload, and which do not
Browser recordings and downloaded WebM files often contain Opus or Vorbis audio that general-purpose music players and voice workflows do not accept. This tool reads the actual first audio stream — whether or not the WebM also has video — and writes a standard 192 kbps stereo MP3 listening copy.
This page has a real two-second fixture made from generated motion, colour and tones — no copyrighted clip and no visitor data. Download the source, run it through the tool, and compare it with the expected profile-1.0.0 output.
⬇ Sample input (WebM) ⬇ Verified expected output
| Check | Input | Expected output |
|---|---|---|
| Codecs | vp9 + opus | mp3 |
| Duration | 2.008 s | 2 s (Δ 0.008 s) |
| File size | 93,031 bytes | 49,581 bytes |
| SHA-256 | 834490a1a8b57748d371d0da60aa553b69f8ccfd3753093a1f8eff657180dae2 | e660d5eb3a9946084a018762e150d5237abd97cc604bc3e771ef0023f4cefb43 |
| Measured time | — | 85 ms in the published environment |
| Validation | Signature + ffprobe | Codec, complete decode and duration: pass |
No confidence score is invented: transcoding is deliberately lossy, so the defensible result is a set of pass/fail structural checks, not “97% accurate.” Your download page exposes the same per-job evidence report as JSON and CSV. See the method, limitations and six-case comparison, or download the anonymous CSV / JSON dataset.
“Accuracy” for this lossy task means the published structural gates below; perceived quality still needs human review of the output.
| Profile | Date | Validation change | Re-test | Result |
|---|---|---|---|---|
| 1.0.0 | 2026-08-16 | Fixed codec profile; EBML DocType / ISO brand checks; rotation-aware dimensions; ffprobe; complete decode; duration tolerance | FH-MEDIA-04 plus the six-profile release gate and adversarial regressions | pass |
WebM is the browser-native media container used by screen recorders, webcam apps, meeting tools and web downloads. It commonly carries VP8 or VP9 video with Opus or Vorbis audio. Browsers handle it well, but many phone editors, televisions, messaging apps and upload forms still require MP4 or MP3 instead.
MP3 is the most broadly compatible compressed audio format. Music players, car stereos, browsers, editors and upload services understand it. It is lossy: converting audio to MP3 removes some information to reduce size, so the original recording remains the right master for future editing.
| WebM | MP3 | |
|---|---|---|
| Type | Video/audio container | Audio |
| Compression | VP8/VP9/AV1 + Opus/Vorbis | Lossy |
| Transparency | Codec-dependent | — |
| Animation | Video | — |
| Typical use | Browser recordings, web video, meetings | Listening, transcription, sharing |
MediaRecorder and browser-based meeting tools commonly write Opus audio inside WebM, even when the recording is effectively a voice note. Opus is efficient, but a legacy player, car stereo or simple transcription upload may ask for MP3. This converter reads the embedded audio rather than assuming every WebM contains video and produces an ordinary listening file.
Transcoding Opus or Vorbis to MP3 is lossy-to-lossy: the output can preserve what you hear, but it cannot recreate frequencies the first encoder removed. For speech, the practical test is intelligibility — names, numbers and quiet speakers — not merely whether the file opens. Keep the WebM for archive, and proofread any transcript made from the MP3.
Yes — there is no sign-up, payment or watermark. The published safeguards are 100 MB input, a 160 MB output cap, a 10 minute selected-stream limit, an 8 minute request-wide deadline and four jobs per visitor per 10 minutes; they are technical limits, not a paid tier.
Media files are handled one at a time. That makes the documented CPU, memory and cleanup limits enforceable and gives the next file a clean job directory. Finish or clear the current file before adding another.
Yes. Native FFmpeg is too large and resource-intensive for a reliable browser-only conversion, so this tool sends the file over HTTPS to our server. It is limited to 100 MB and 10 minutes and uses an isolated temporary job directory. Normal cleanup removes that directory after success, failure, cancellation or timeout; startup and five-minute sweeps remove a forced-crash leftover once it is older than the request deadline. Media files are never intentionally retained.
Yes, provided the file contains a decodable audio stream. A WebM with video but no audio cannot produce an MP3 and is refused with a clear message.
filehugger.com