Why this is the fastest WebM to MP4 converter on the web
WebM to MP4 always requires a full transcode (VP8/VP9 cannot live inside an MP4 container). Browser ffmpeg.wasm tools handle that single-threaded with a ~2 GB cap and often 5–10× slower than native; they also outright fail on bigger files. We rebuilt the pipeline: presigned upload to the nearest Backblaze B2 POP, native ffmpeg on our server, output delivered through Bunny CDN. A 1080p clip usually clears in 5–10 seconds.
When you need to convert a WebM to MP4
Every browser-based screen recorder hands you a .webm — Chrome's built-in recorder, OBS's WebRTC mode, Loom downloads, our own Clipy web recorder. Most of the time the next thing you want to do is upload to iMessage, drop in a Slack DM, or send to a Windows colleague — and that is when the universal compatibility gap bites. Converting WebM to MP4 once solves it permanently.
No file size limit — up to 500 MB
Most online converters impose a 50–200 MB cap because they pay per gigabyte of bandwidth and CPU. Our pipeline is direct-to-B2 storage with a flat conversion cost, so the cap sits at 500 MB — large enough to cover almost every screen recording. For multi-hour 4K captures, the Clipy desktop app ships native ffmpeg with no cap at all.
Sister tools
Going the other direction? MP4 to WebM converter re-encodes to VP8 + Vorbis for HTML5 video, Google Slides embeds, and open-source players. Already have a working MP4 you want to compress further? Video compressor. Need to swap containers between H.264 sources? MOV to MP4 converter handles QuickTime / ProRes / HEVC inputs.