JSM-Video.com is a free online video converter that runs 100% in your browser. Convert MP4, MOV, MKV, WebM, AVI and more to MP4, MP3, WAV, AAC, GIF and 20+ other formats — plus rotate, flip, and mute videos — with no uploads, no accounts, no watermarks, and no file-size games.
Most online converters upload your file to a server, convert it there, and send it back. That means waiting on uploads, trusting strangers with private footage, and hitting paywalls for large files. JSM-Video.com does the opposite: we compile FFmpeg — the same professional engine behind YouTube and VLC — to WebAssembly (WASM), so it runs directly in your browser tab. Your video is decoded, converted, and re-encoded on your own device. There is no upload endpoint at all, so your files cannot leave your computer even in theory.
The ~25 MB engine downloads once and is cached by your browser, so repeat conversions start instantly. Conversion speed depends on your device and the file size — modern laptops handle typical phone videos in seconds to a couple of minutes.
Browser-based conversion works best under 500 MB per file; the hard cap is 1 GB to protect browser stability. Very long 4K footage converts more slowly — for feature-length projects, a desktop tool like HandBrake or Shutter Encoder is still the better choice. WAV extraction is instant because it needs no re-encoding.
JSM-Video.com is an independent project by the maker of JSM-Image.com (free private image tools) and JSM-Options.com (options trading education). The philosophy is the same everywhere: free tools, honest labeling, and your data stays yours. Questions? Use the contact page.
