Free Online Video Converter

Convert between MP4, MOV, MKV and WebM in your browser. Streams the target format can hold are copied without re-encoding, so most conversions finish in seconds.

The converter is ffmpeg compiled to WebAssembly. It downloads once (30 MB) when you pick your first file, then stays in your browser cache.

Streams the target container can hold are copied across without re-encoding, so quality is untouched and it finishes in seconds. Only what the target cannot hold gets re-encoded, and each row tells you which happened.

Your file is processed by your own browser and never uploaded. The engine itself is a one-time 30 MB download the first time you use it, and after that it comes out of your browser cache.

How to use Video Converter

  1. 1Pick the output format below, then drop one or more videos onto the box above.
  2. 2Each file is inspected first. Streams the target container can hold are copied unchanged; only incompatible ones are re-encoded, and the row says which happened.
  3. 3Download files individually, or grab everything as a zip.

Copy first, encode only when forced

A video file is a box of streams, and most "conversion" jobs only need a different box. This converter is built around that fact: it reads what is inside your file, checks it against what the target container accepts, and copies everything it can. A copied stream costs no time worth mentioning and no quality at all, because no frame is ever decoded.

Re-encoding happens only where it is genuinely forced, such as VP9 video heading into an MP4, or H.264 heading into a WebM. Those runs are slower than real time in a browser, and the interface treats that honestly: the row says re-encoding while it happens, shows a percentage, and the cancel button actually stops the work rather than just hiding it.

Choosing a target, practically

MP4 with H.264 is the least interesting and most correct answer for almost everyone: phones, TVs, browsers, editors and web forms all take it. MOV is worth choosing when an Apple-centric pipeline asks for it by name. MKV holds nearly any stream you throw at it unchanged, which makes it the fast target for archiving odd files. WebM is the open format the Chromium world favours; going to it always re-encodes here, so reserve it for when a platform requires it.

For pulling the soundtrack out of a video there is a dedicated audio converter, and the GIF pages handle animated output, each with the controls that job actually needs.

Limits, stated plainly

Files up to 500 MB are accepted. The first file triggers a one-time engine download whose size the page states up front. Everything runs locally: your footage never leaves your browser, whatever is in it.

Frequently asked questions

Which conversions are instant and which are slow?
Anything where the target container can hold the source's codecs is instant, because the streams are copied rather than re-encoded. MOV to MP4, MP4 to MOV and almost everything into MKV fall in that class. Conversions into WebM, and WebM into anything Apple-flavoured, genuinely re-encode and run slower than the clip's duration. The row for each file tells you which kind you got, while it runs and after.
Which output format should I pick?
MP4 unless you have a reason. It plays on effectively everything made in the last fifteen years. MOV matters when a specific Apple-centric workflow demands it, MKV is the archivist's box that holds anything, and WebM serves the open-web stack. If you just need the file to work somewhere, MP4 is the answer.
Does converting lose quality?
A copied stream loses nothing, and is bit-identical to the source. A re-encoded one is compressed again, which costs some quality by nature; the encoder matches its bitrate to the source's resolution and frame rate to keep that loss hard to see. The honest summary is that this tool loses zero quality whenever the formats allow it, and says so per file.
What happens to subtitles and extra audio tracks?
Subtitle and data tracks are dropped, and only the first audio track is kept. Containers disagree wildly about these, and carrying them across unreliably is worse than being clear. If multi-track material matters to you, a desktop tool is the right place for it.
Is there a GIF option?
GIF is deliberately its own page, because it is not really a video format; it needs different controls for frame rate and width. Use our video to GIF tool for that, and the GIF to MP4 page for the reverse.

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