MP4, WebM, MOV, MP3, WAV, AAC, GIF and more. Powered by FFmpeg.wasm — no upload to any server.
Files are processed locally by FFmpeg.wasm. Nothing is uploaded.
Convert between popular video and audio formats.
Conversion happens instantly on your device.
Video conversion normally happens on a server, because it is heavy work. These tools do it on your own device instead, using a build of FFmpeg compiled to WebAssembly that runs inside the page.
The trade is honest and worth understanding. It is slower than a server would be, and the first run has to download the conversion engine, which is a sizeable one-time cost. In exchange your video is never uploaded. For anything personal, that is usually the better bargain, and it is the reason there are no file-size limits driven by what we are willing to host.
Expect roughly real-time speed or slower on a laptop, and slower again on a phone. A long clip is a genuine wait rather than an instant result, and closing the tab cancels the work, because the work is happening in the tab.
MP4 with H.264 is the right default and the answer whenever you are unsure. Every phone, browser, television and editing program made in the last fifteen years plays it. If a file has to work somewhere you cannot test, this is the format that works.
WebM produces smaller files at the same visual quality and is well supported in browsers, but poorly supported by desktop software and some devices. Choose it for the web, not for sending to people.
GIF should be a last resort for anything longer than a few seconds. It cannot store more than 256 colours and has no real compression for motion, so a short clip converted to GIF is frequently larger than the video it came from, and looks considerably worse.
Converting audio out of a video, to MP3 or WAV, is much faster than a video conversion because the picture is simply discarded rather than re-encoded.
Resolution is the strongest lever by a wide margin. Halving the width and height removes three-quarters of the pixels, and the file shrinks roughly in proportion. A clip destined for a phone screen or a messaging app rarely needs to stay at 4K.
After that, trim length before you touch quality. Cutting ten seconds off the front removes ten seconds of data with no visible cost anywhere else, which is not true of lowering the bitrate.