MOV · MKV · WEBM → MP4 · WEBM
Video converter
Move a video between containers — MOV, MKV or WEBM into MP4, or MP4 into WEBM — right here in the tab. Nothing is uploaded, and a compatible video is often repackaged in seconds.
MP4 (H.264 + AAC) plays on virtually everything, from phones to car stereos. WEBM stays smaller at the same quality but is mostly a browser format.
At a glance
- Price
- Free
- Account
- None needed
- Upload
- None — the video is read and written in your browser tab, nothing is sent to a server
- Input
- MP4, MOV, MKV, WEBM, M4V
- Output
- MP4 (H.264) or WEBM (VP9)
- File size
- 1 GB per file
- Works on
- Recent Chrome, Edge, Firefox or Safari (Firefox 130+, Safari 16.4+)
How to convert a video
Add the video
Drop a MOV, MKV, WEBM or MP4 file on the box above — one file per conversion keeps the memory use honest.
Pick the output
MP4 is the safe choice for sharing and playing anywhere. WEBM keeps the VP9 codec and is the smaller option for the web. Leave the resolution on Original to keep every pixel.
Download the result
The progress bar shows the encode as it runs; when it fills, the file is ready to download with a name that keeps the original.
Repackaging versus re-encoding
A video file is a container around encoded tracks. When the tracks are already in the right format for the target — an H.264 + AAC MOV heading for MP4, or VP9 + Opus WEBM heading for WEBM — the container is rewritten around them untouched, which is fast and lossless.
When the codecs do not match, the video is decoded and encoded again on your device's own hardware codec. That takes longer and costs a little quality, which is why the conversion asks before shrinking the resolution. Either way the bytes stay on your device: no upload, no queue, no server.
Video converter questions
Is my file uploaded anywhere?
No. The reading and writing both happen in this browser tab with WebCodecs, the same machinery that plays and records video natively. Nothing is sent to a server.
Why did converting a MOV take only a second?
Because nothing needed re-encoding: the video and audio tracks were already H.264 and AAC, so the converter simply rebuilt the MP4 container around them — a lossless, near-instant operation.
Which codecs do the outputs use?
MP4 carries H.264 video and AAC audio; WEBM carries VP9 video and Opus audio. Those combinations play in every current browser and on every modern device.
Can I shrink the video while converting it?
Yes — pick 1080p or 720p under Resolution. Anything above the source height is ignored, so a 480p recording stays 480p rather than being stretched.
What does the converter not support?
Codecs your browser cannot decode, such as some professional or older camera formats. The tool says so plainly instead of producing a broken file.