Convert between MP4, MOV, MKV, WebM and AVI without uploading anything. Where the formats allow it the file is rewrapped rather than re-encoded — seconds instead of minutes, and not a single pixel changes.
Free and unlimited — no account, no watermark, and the file never leaves your browser. Big files and batch runs are faster in the desktop app.
An MKV and an MP4 holding the same H.264 video are the same picture data in a different wrapper. Rewriting the wrapper — remuxing — takes about a second and is bit-for-bit lossless. Converters that upload your file re-encode it every time regardless, which is why they are both slower and worse. This one tries the rewrap first and only re-encodes when the target container genuinely refuses the codec.
Conversion runs through an FFmpeg build compiled to WebAssembly inside your own browser tab. Nothing is uploaded, there is no queue behind other people's files, and no copy of your video sits on someone's S3 bucket waiting for a retention policy. That matters more than it sounds when the footage is a client's.
Before you press convert, the page says whether this pair is a rewrap or a re-encode — and for the one pair that is always slow, H.264 into WebM, it explains why: WebM accepts VP8 and VP9 only, so the video has to be rebuilt from scratch. No other free converter distinguishes the two, so every conversion feels equally arbitrary.
Open this page. The converter is on it — there is no sign-up step and nothing to install.
Pick an MP4, MOV, M4V, MKV, WebM or AVI file. It is read straight from disk into the browser tab, not uploaded.
Choose MP4, MOV, MKV or WebM. The note under the buttons tells you whether this pair rewraps in seconds or needs a full re-encode.
Press Convert. The first run downloads the 31 MB video engine once and caches it; every run after that starts immediately.
Play the converted file in the page to check it, then download it. Nothing is watermarked and there is no daily limit.
Last updated August 2026
| Capability | CloudConvert | FreeConvert | Zamzar | ViralMint |
|---|---|---|---|---|
| Where the file is processed | Their servers | Their servers | Their servers | Your browser tab |
| Rewraps when codecs allow | Re-encodes | Re-encodes | Re-encodes | Yes — seconds, lossless |
| Free-tier limit | 25 conversions/day | 1 GB, capped daily | 50 MB per file | None |
| Account required | For anything past the free tier | For larger files | For most formats | No |
| Exotic formats (FLV, WMV, 3GP…) | Yes | Yes | Yes — hundreds | No — six common ones |
highlighted column = clearer fit for that capability. Tied capabilities are left unmarked.
It is free with no account and no watermark. The practical ceiling is 200 MB, which is a memory limit rather than a policy one — the whole file is held in the browser tab while it works. Past that, the ViralMint desktop app runs the same FFmpeg natively with no cap.
Not when the conversion is a rewrap, which covers most pairs: MP4 to MKV, MOV to MP4, AVI to MKV and so on just move the same encoded streams into a different container, so the output is bit-for-bit the same video. A real re-encode does lose a generation — that happens when you convert to WebM, or out of a container whose codec the target does not accept. The page tells you which one you are about to do.
Because only one of them is a real conversion. MKV accepts the H.264 video your file already contains, so that is a rewrap — measured at 0.3 seconds for a five-second 720p clip. WebM is defined to hold VP8 or VP9 only, so the picture has to be decoded and re-encoded from scratch; the same clip takes about 1.8 seconds. Both are fast, but the gap grows with length: a rewrap is roughly constant, a re-encode scales with the duration of the video.
MP4, MOV, M4V, MKV, WebM and AVI in; MP4, MOV, MKV and WebM out. That is deliberately a short list of formats people actually have, rather than the hundreds of legacy codecs the server-side converters advertise — those need a server precisely because nobody can ship every decoder to a browser.
FFmpeg itself, compiled to WebAssembly. It is fetched once, cached by the browser, and shared with the other in-browser tools on this site — so the first conversion pays for it and trimming, compressing or extracting audio afterwards costs nothing extra.
That is a separate tool, because it is a different job — see the audio extractor, which pulls the soundtrack out as MP3, M4A or WAV. Extracting AAC audio from an MP4 into an M4A is itself a stream copy, so it is instant and lossless.
The Video Converter ships inside the free ViralMint desktop app — no subscription, no watermark, no per-minute cap. Download once, use on as many videos as you want.
