WebM to MP4 Converter
Convert WebM to MP4. Batch-ready, stays in your browser.
Drop files here
or click to browse · paste from clipboard
Accepts .WEBM · Up to 1,000 files
How it works
Drop your files
Drag and drop, click to browse, or paste from clipboard. Up to 1,000 files at once.
Choose settings
Adjust quality, format, and other options to match your needs.
Click Convert
Everything runs in your browser via WebAssembly. WebM to MP4 Converter happens locally — no server involved.
Download
Download files individually or grab all at once as a ZIP.
Frequently asked questions
WebM is an open format designed for the web — Chrome and Firefox play it natively, but support on Apple devices, Windows Media Player, and most video editors is limited. MP4 with H.264 plays everywhere without plugins or format negotiation. If you need to share a WebM recording or export a screen capture, MP4 is the compatible choice.
WebM files contain VP8 or VP9 video and Vorbis or Opus audio. ffmpeg.wasm handles all four codecs and re-encodes them to H.264 video and AAC audio, which is the standard MP4 payload for broad device support.
Re-encoding from VP8/VP9 to H.264 involves transcoding, so there is a small quality reduction — this is unavoidable when changing codecs. At CRF 23 (Better) the difference is not visible on most content. Use Best (CRF 18) if you need to preserve as much quality as possible.
Quality controls the H.264 CRF (constant rate factor). Best (CRF 18) produces the sharpest image at the cost of a larger file. Good (CRF 28) cuts file size noticeably with a visible quality reduction on detailed footage. Better (CRF 23) is the balanced default.
Yes. Drop as many as you need. Each file converts separately in your browser using ffmpeg.wasm, and the results download as a ZIP. No queue, no upload, no per-file count limit.
Never. Conversion runs entirely in your browser using WebAssembly. Your files do not leave your device at any point.