Video Converter
Convert video between MP4, WebM, MKV and MOV with a quality choice, in your browser. Free, private, no signup or upload.
About the Video Converter
This free video converter changes your video between the most common formats — MP4 (H.264), WebM (VP9), MKV and MOV — with a simple quality choice. Whether you need an MP4 for maximum compatibility, a WebM for the web, or a MOV for an Apple workflow, the tool produces a ready-to-use file in one step.
All conversion runs in your browser through FFmpeg WebAssembly, so your video is never uploaded. The engine (about 30 MB) downloads from a CDN the first time you use any converter here and is then cached, which is why the first conversion takes longer than the rest.
MP4, MKV and MOV outputs use fast H.264 encoding; WebM uses VP9, which is efficient but noticeably slower to encode in the browser. Converting re-encodes the video and cannot add quality beyond the source, but a higher quality setting preserves more detail. Files up to 100 MB are supported.
How to Use the Video Converter
- 1Choose a video file, up to 100 MB.
- 2Pick the target format and a quality setting.
- 3Click Convert Video and wait for the progress bar.
- 4Preview the result (where supported) and download it.
Frequently Asked Questions
Is my file uploaded to a server?
No. All processing runs in your browser using FFmpeg compiled to WebAssembly. Your file never leaves your device — only the converter engine is downloaded, once.
Why is the first run slow?
The first time you use any converter here, the browser downloads the FFmpeg core (about 30 MB) from a CDN and compiles it. It is then cached for the session, so later runs are much faster.
Which format should I choose?
MP4 (H.264) is the most compatible choice for phones, browsers and editors. WebM (VP9) is efficient and ideal for websites. MKV and MOV suit specific workflows and archiving.
Why is WebM slower to convert?
WebM uses the VP9 codec, which is more computationally intensive to encode than H.264 — especially single-threaded in the browser. It produces efficient files but takes longer, so expect a slower run.
Is there a file size limit?
Yes, 100 MB per file. Because everything runs in your browser's memory, very large files can be slow or run out of memory. Trim long clips first if you hit the limit.