Free · No upload · No sign-up
Convert MP4 to WebM
Turn MP4 into WebM (VP9 + Opus) for open-web playback and smaller HTML5 <video> files — entirely in your browser.
MP4WebM
Checking browser capabilities...
Drop your .mp4 file here
Converted to WebM in your browser.
Why this tool
Open codec
VP9 + Opus is royalty-free and plays natively in Chrome, Firefox, Edge, and Safari 14.1+.
Private by default
Conversion runs in your browser via ffmpeg.wasm. No upload, no retention.
Smaller files
At matched visual quality VP9 typically produces 20–40% smaller files than H.264 — ideal for self-hosting.
How to convert MP4 to WebM
- 1Drop your .mp4 file above.
- 2Pick a quality preset (Balanced gives the best size/quality trade-off).
- 3Click Convert. Progress and ETA update live.
- 4Download the .webm file. The source MP4 stays untouched.
Frequently asked questions
- Why convert MP4 to WebM?
- WebM is the open-web format of choice: royalty-free codecs, first-class HTML5 <video> support, and smaller files at comparable quality. Use it when you host video on your own site and want broad browser support without patent hassles.
- Will the quality drop?
- VP9 is a modern codec and at the Balanced preset is visually indistinguishable from the source for most content. High preset is near-lossless for short clips.
- How long does the conversion take?
- Expect roughly real-time to 2× real-time on a modern laptop. VP9 is slower than H.264 but the quality/size gains are worth it.
- Does it upload my file?
- No. The MP4 never leaves your browser tab — ffmpeg.wasm runs locally via WebAssembly.
- Is there a file size limit?
- Up to 4GB in-browser. Very large files may exhaust memory on low-RAM devices; in that case, compress or trim first.
- Will this work on Safari?
- Encoding runs in WebAssembly, so it works in Safari 16.4+. Playback of the resulting WebM needs Safari 14.1+. Older iOS devices will need MP4 instead.