Upload an MP4 file and convert it to WebM. When the codecs already fit the target container, the conversion is lossless and near-instant; otherwise the video is re-encoded.
Your file never leaves your device. All processing happens right in your browser, and nothing is uploaded to a server.
WebM accepts only open codecs (VP8, VP9, AV1 video with Opus or Vorbis audio), while MP4s typically carry H.264 and AAC. Those streams are re-encoded to WebM codecs, so this conversion does real encoding work and takes time proportional to video length.
The encode targets high quality; for most footage the visual difference from the source is negligible.
WebM is royalty-free and plays natively in every modern browser, making it a favorite for embedded video, web games, and platforms that prefer open formats. VP9 also compresses efficiently, often beating H.264 on size at similar quality.