Convert
Convert video to MP4 without uploading it
Convert MOV, WebM, MKV and AVI videos into universally playable MP4 files locally in your browser.
For the best results: Balanced quality (CRF 23) is visually identical to the original for most footage; choose Compact only when file size matters more than fine detail. Long videos take a while, the encode runs on your own processor, so keep the tab open.
Advanced settingsoptional, defaults work well
Converted entirely in your browser, your files are never uploaded. Very large files depend on your device's memory.
What is Video Converter?
Video Converter is a free file converter that re-encodes MOV, WebM, MKV and AVI videos into standard MP4 files with H.264 video and AAC audio, entirely inside your browser. The video is processed by an ffmpeg engine running inside your browser, so your footage is never uploaded anywhere. There is no queue and no watermark, and after the first load it keeps working without a connection.
- ✦Runs entirely in your browser. Nothing you enter is ever uploaded
- ✦No account, no sign-up, and no data leaves your device
- ✦Works offline once the page has loaded
See it in action
A screen recording saved as WebM will not play in the client's ancient conference-room player, which only knows MP4.
What you drop in
recording.webm, defaults (the advanced panel offers resolution, fps, rotate, flip, audio volume and mute)
What you get
recording.mp4 in H.264 with AAC audio, playable basically everywhere. In testing a sideways phone clip rotated 90 degrees came out with its dimensions correctly swapped, 320x240 to 240x320.
Tip: The 31 MB conversion engine loads once on first use and then stays cached, so the second conversion starts instantly.
Use cases
What people use it for
Turn an old AVI holiday video from a backup drive into an MP4 a modern TV recognizes.
Convert MKV recordings of your own gameplay into MP4s that drop straight into a PowerPoint deck.
Standardize footage from several borrowed cameras into uniform MP4 files before a community project edit.
Who uses Video Converter?
Family archivists
modernize decades of AVI and MKV home footage into MP4s that every relative's phone and TV can open
Teachers
convert classroom clips from whatever camera recorded them into MP4s that embed cleanly in lesson slides
Small business owners
prepare supplier and event footage as MP4 so it plays in presentations, on websites, and in client emails
How it works
- 1Choose your files. They open in your browser, not on a server.
- 2Your device converts, compresses, or resizes them locally, with no upload.
- 3The converted files download straight back; nothing is kept anywhere.
Tips for the best results
- Convert from the original recording rather than a copy another tool has already re-encoded.
- Pick a lower CRF for footage you plan to edit later, since editing benefits from headroom.
- Plug a laptop in before converting long files, because sustained encoding drains batteries quickly.
- Close memory-hungry tabs first, as the whole file is processed in browser memory.
- Keep the source file until you have watched the MP4 through at least once.
FAQ
Frequently asked questions
What is the difference between a container and a codec?
A container such as MP4, MKV, or AVI is the box: it holds video, audio, and subtitle streams together with timing information. A codec such as H.264 or AAC is how each stream inside is actually encoded. A file can fail to play because a device dislikes the box, the encoding, or both, which is why conversion here rewrites everything to the safest pairing.
What does the CRF quality setting control?
CRF stands for constant rate factor, the H.264 encoder's quality dial. Lower numbers spend more data and preserve more detail; higher numbers compress harder and let fine texture soften. Unlike a fixed bitrate, CRF holds visual quality steady across the whole clip, spending extra data on busy scenes and less on static ones, so file size varies with content.
Why convert everything to H.264 and AAC specifically?
Because that pairing inside MP4 is the closest thing video has to a universal language. Smart TVs, phones, browsers, editing suites, and office software have all shipped H.264 and AAC decoders for well over a decade. Newer codecs compress more efficiently, but none approaches the certainty that this combination will simply open and play wherever the file ends up.
Does my video leave my computer during conversion?
It does not. The page carries ffmpeg compiled to WebAssembly, so decoding and re-encoding happen inside your browser tab and the finished MP4 downloads from your own memory. Family footage, work recordings, and anything sensitive stays on the device it started on, with no upload progress bar because there is genuinely no upload.
Why does converting a long video take several minutes?
Re-encoding means decoding every frame and compressing it again, and here that arithmetic runs single-threaded on your own processor rather than on a rack of servers. Expect it to be noticeably slower than a desktop app, with a long clip taking minutes. The trade is deliberate: patience in exchange for footage that never travels anywhere.
Is this an AI video converter?
No. It is ffmpeg, the same open-source engine professional software relies on, compiled to run inside your browser tab. The conversion is deterministic: identical input and settings always produce an identical MP4. Nothing is guessed or generated, no footage is sent to a remote model, and the result is predictable every single time.
How do I convert a video to MP4 for free without installing software?
Open this page, drop the MOV, WebM, MKV, or AVI file in, pick a quality level, and download the MP4 when encoding finishes. Nothing installs and no account exists to create. The one download is the conversion engine itself, roughly 31 MB, which your browser fetches once and then keeps cached.
What is a good CRF value for H.264?
Values in the low twenties are the everyday sweet spot, where most viewers cannot tell the output from the source. Go lower when the footage will be edited again or shown on a big screen, and higher when small size matters more than fine detail. When unsure, test a short clip at two settings and compare.
Are there any usage limits?
None. Everything is generated locally in your browser, so there is no server cost, no metering, and no daily cap, use it as many times as you like, completely free.
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