Drop a webm, mkv, mov, avi, or any video file and convert it to MP4 right in your browser. No upload. No signup. Your file never leaves your device.
Click the drop zone (or drag your file onto it) and pick any video — webm, mkv, mov, avi, flv, and more all convert to MP4 (H.264 video + AAC audio). The first time you use it, your browser downloads the FFmpeg engine (~25 MB, cached after), then the conversion runs locally. When it's done, the Download MP4 button appears.
Most online video converters ask you to upload your file to their server, process it, then let you download the result. That means your video leaves your device — slow for big files, and a privacy concern for personal content. This tool runs the full FFmpeg conversion in your browser via WebAssembly, so the file never leaves your machine. The trade-off is speed: browser-based conversion is slower than a native converter with hardware encoding, so it's best for short-to-medium clips. For very large files, a native desktop converter is faster.