Convert WebM to MP4 in Your Browser
Turn screen recordings and WebM clips into universally playable MP4 (H.264/AAC) right in your browser — hardware-accelerated, nothing uploaded.
Convert a WebM file to MP4 directly in your browser. MediaStand decodes the VP8/VP9 video and Opus audio with your device's hardware, re-encodes to H.264 and AAC — the most widely playable combination — and keeps the original resolution. Your file never leaves your device, and it works offline once loaded.
Choose a file or drop it here
🔒 Processed locally — never uploaded.
WebM is what browsers produce: screen recorders, MediaRecorder apps and video calls all love it — but iPhones, TVs, editors and many messengers still don't. This converter turns WebM (VP8/VP9 + Opus) into a standard MP4 with H.264 video and AAC audio at the original resolution. On supported browsers the whole pipeline runs on your graphics hardware, so a typical screen recording converts in seconds, not minutes. Everything happens on your device — nothing is uploaded.
How it works
- Pick a WebM file from your device or drop it into the box.
- The tool decodes VP8/VP9 + Opus and re-encodes to H.264 + AAC using hardware acceleration when your browser supports it (a badge tells you which engine ran).
- Press the download button — or for very large files, choose a save location up front and the MP4 streams directly to your disk.
Common uses
- Share a screen recording with iPhone or iPad users who can't open WebM.
- Upload browser-recorded clips to platforms and CMSs that only accept MP4.
- Import WebM footage into video editors that reject VP8/VP9.
- Archive meeting or webinar recordings in the most future-proof container.
Supported formats and limits
| Input | WebM (VP8 or VP9 video, Opus or Vorbis audio) — the format browsers and screen recorders produce |
|---|---|
| Output | MP4 — H.264 video + AAC audio at the original resolution (bitrate capped below the source, so files never grow) |
| Speed | Hardware path: seconds for typical clips. Compatible fallback: roughly 1.5x video length |
| Maximum file size | 500 MB in-memory; up to 1.5 GB in Chrome/Edge via direct-to-disk streaming |
| Where it runs | Entirely in your browser (WebCodecs + WebAssembly) — keeps working offline once loaded |
Frequently asked questions
Is my video uploaded during conversion?
No. Decoding and encoding run inside your browser — with WebCodecs hardware acceleration when available, or a WebAssembly FFmpeg fallback. Your file never leaves your device.
Why convert WebM to MP4 at all?
WebM plays great in browsers but poorly almost everywhere else: iPhones, TVs, editors and many apps expect MP4 with H.264/AAC. Converting once makes the clip playable virtually anywhere.
Does the conversion lose quality?
It is a re-encode (VP8/VP9 cannot live inside a standard MP4), but the target bitrate is matched to your source, so visual quality stays close to the original and the file never gets bigger.
What happens to the audio?
Opus audio is decoded and re-encoded to AAC — including automatic stereo downmix for surround sources and sample-rate conversion when your device's encoder needs it.
Is there a size limit?
500 MB for the in-memory path in any browser. In Chrome and Edge, files up to 1.5 GB are processed in streaming mode: you pick a save location first and the MP4 is written to disk as it is produced.
Is this free?
Yes — free, no signup, no watermark, no queue. Processing happens on your device, so there is nothing for us to meter.