Is my video uploaded anywhere?

No. ffmpeg.wasm processes everything inside your browser via WebAssembly. The file never leaves your device.

Does it work on mobile?

Yes. Works on iPhone Safari and Android Chrome without installing any app.

Will MP4 work in older players too?

Yes. H.264 baseline support goes back decades and works on virtually every modern device, plus a huge range of legacy hardware including older smart TVs, game consoles, and basic media boxes.

Does it re-encode audio too?

Yes, audio is re-encoded to AAC at 128 kbps for guaranteed MP4 compatibility. AAC at 128 kbps sounds great for speech and good for music.

Convert to MP4

Convert WebM, MOV, AVI, MKV, or FLV to MP4 (H.264) — universally compatible output.

100% client-side · no upload

Video file (WebM, MOV, AVI, MKV…)

Settings Quality preset

Load a file to begin.

How to use

Choose your video file (WebM, MOV, AVI, MKV, or any other format).
Select a quality preset. Balanced (CRF 23) is the recommended starting point.
Click Convert to MP4 and wait for encoding to finish. Download the universally compatible MP4.

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More ways to use this tool

Frequently Asked Questions

Is my video uploaded anywhere?: No. ffmpeg.wasm processes everything inside your browser via WebAssembly. The file never leaves your device.
Does it work on mobile?: Yes. Works on iPhone Safari and Android Chrome without installing any app.
Will MP4 work in older players too?: Yes. H.264 baseline support goes back decades and works on virtually every modern device, plus a huge range of legacy hardware including older smart TVs, game consoles, and basic media boxes.
Does it re-encode audio too?: Yes, audio is re-encoded to AAC at 128 kbps for guaranteed MP4 compatibility. AAC at 128 kbps sounds great for speech and good for music.

Last updated: 2026-05-20 By jarvisbox