Video converter that never uploads your file

Drop in a MOV, MKV, WebM, AVI or almost anything else and get MP4, WebM, MOV, GIF or MP3 back. FFmpeg runs inside this tab, so the video stays on your device.

Drop a video file hereThe converter loads in your browser.
  • No upload. FFmpeg runs as WebAssembly inside this tab; your file never leaves the device.
  • No limits we impose. No accounts, watermarks or file caps. Your device's memory is the only ceiling.
  • Remux first. When the codecs already fit the new format, streams are copied in seconds with zero quality loss.

What runs in your browser, and what doesn't

VideoConvert uses ffmpeg.wasm, the FFmpeg toolkit compiled to WebAssembly. It is the same code that powers most desktop converters, running on your CPU inside the page. That buys privacy, but it has honest limits:

  • Speed. The engine is single-threaded and has no GPU access. Remuxing (MOV→MP4, MKV→MP4 with compatible codecs) is near-instant. Real re-encoding of 1080p H.264 typically runs at roughly real-time to a few times slower on a laptop, and slower on phones. 4K and HEVC sources are the slowest.
  • Memory. WebAssembly can address about 2 GB. Input files are read straight from disk, but the output is built in memory, so very large outputs can fail. Phone browsers often allow far less; keep phone jobs under a few hundred MB.
  • Formats we can't write. HEVC/H.265, VP9 and AV1 encoding is not offered: in this WebAssembly build x265 stalls, VP9 runs out of memory and AV1 isn't compiled in. We read all three fine, and write H.264, VP8, MPEG-4, MPEG-2, Theora, WMV, FLV and ProRes Proxy.
  • DRM. Protected files (iTunes M4V, streaming downloads, encrypted DVDs) can't be converted by any open tool.
  • Phones. Keep the screen on and the tab in front. iOS and Android pause background tabs, which stops the conversion.

Your browser's codecs

Every browser decodes and plays a different set of formats. The format page tests yours live and lists all 50+ formats the converter reads.

Check my browser

Shrinking, not converting?

This site is about changing formats. If you need a video under a size limit for email, Discord or WhatsApp, SqueezeVideos compresses to a target size, also in the browser.

Questions

Is this video converter really free with no upload?

Yes. The converter is FFmpeg compiled to WebAssembly and runs in your browser tab. Your file is read directly from your disk and the result is saved back to it. There is no server that receives your video, so there is nothing to charge for per file and no watermark.

Which formats can I convert?

It reads more than 50 container and codec formats, including MP4, MOV, MKV, WebM, AVI, WMV, FLV, MPEG/VOB, MTS/M2TS, 3GP, MXF, HEVC and animated GIF, plus common audio files. It writes MP4, WebM, MOV, MKV, AVI, WMV, FLV, MPEG, TS, OGV and GIF, and audio as MP3, M4A, WAV, FLAC, OGG and Opus.

Why was my conversion finished in two seconds?

Because it was a remux. When the video and audio codecs are already allowed in the target container (for example H.264 + AAC from MOV into MP4), the streams are copied into the new container without decoding. That is fast and lossless.

Does it work on iPhone and Android?

Yes, in Safari, Chrome and Firefox on phones, within the memory limits phones give a browser tab. Short clips and remuxes work well; long 4K re-encodes are better done on a computer. Keep the screen on during the conversion.

Can I convert to HEVC (H.265)?

No. We read HEVC but do not encode it, because the x265 encoder does not run reliably in single-threaded WebAssembly. Use HandBrake or desktop FFmpeg for HEVC output.

How do I make a video file smaller?

Choose "Smaller file" or a lower resolution here for a quick result. For hitting an exact size target (say, under 25 MB for Discord or email), SqueezeVideos is our sister tool built for that.