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WebM to MP4 Converter

Convert WebM videos to MP4 locally with WebAssembly. Nothing is uploaded — encoding stays in your browser.

Privacy First

Conversion runs entirely in your browser via FFmpeg.wasm. We do not upload, store, or access your videos.

Drag and drop WebM files here, or

Supports .webm — longer clips take longer to encode

About WebM to MP4

WebM is common from browser recordings (Chrome, Firefox, Edge). MP4 with H.264 plays more reliably on phones, messaging apps, and older devices.

This tool re-encodes video to H.264 and audio to AAC in your browser using FFmpeg compiled to WebAssembly — the same approach as Webcam Capture's Download MP4.

Notes:

  • Files are processed one at a time (shared encoder)
  • First conversion may take a few seconds to load the WASM core
  • Long or high-resolution clips need more time and memory
  • Nothing leaves your device

Recorded a clip with Webcam Capture? You can also convert there, or drop the WebM file here.

Frequently Asked Questions

Are my videos uploaded when I convert WebM to MP4?
No. Conversion runs locally in your browser with FFmpeg.wasm. Your videos never leave your device.
Why convert WebM to MP4?
WebM is common from browser recordings, but MP4 with H.264 plays more reliably on phones, messaging apps, and older devices.
How long does conversion take?
The first run loads a WebAssembly encoder (a few seconds). After that, time depends on clip length and resolution — short clips are usually quick; long 1080p videos take longer.
Can I convert multiple files?
Yes. Drop several WebM files at once. They convert one at a time using a shared browser encoder.
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