Convert a WebM video (downloaded from YouTube, Twitter, or a web recorder) to MP4 — fast, in your browser, no upload.
Videos you download from the web often come as WebM — it's the default format YouTube, screen recorders, and most web-based video tools save in. The problem: MP4 is still the lingua franca for video editors, phones, TVs, and social media uploads. Handing someone a WebM often means answering "why won't this play?"
Converting a WebM to MP4 typically involves re-encoding the video track because WebM usually carries VP9 or AV1, and MP4 players overwhelmingly expect H.264 or H.265. We handle that inside your browser using WebCodecs, which uses your GPU for the encode — so even a long video is done in a few minutes, not hours. The audio (Opus or Vorbis) is re-encoded to AAC for MP4 compatibility.
WebM is Google's open container for the web, typically carrying VP9 or AV1 video and Opus or Vorbis audio. It plays natively in browsers but many desktop tools and devices prefer MP4.
MP4 is the most widely supported video container. Output here is mastered with fast-start so it plays instantly in web and mobile players.
Drag a WebM onto the converter above, or click the box to pick one from your device.
We've preselected MP4 as the output format. Change it from the dropdown if you want a different target.
Click Convert and wait for the progress bar to finish. Download the MP4 when it's ready.
Convert a WebM video to an MP3 audio file — perfect for grabbing audio from downloaded YouTube clips or screen recordings.
Convert an MKV (Matroska) video to MP4 so it plays on phones, TVs, and every video editor — free, in your browser.
Convert an MP4 to WebM for smaller file sizes and open-source-friendly web delivery.