About
One page, one job
Clipunder re-encodes a video in your browser so it lands under a size limit — the limits Discord uses for uploads, and any other limit you type in.
What it is
A single static page. You pick a target size, drop a clip, and the page decodes it, encodes H.264 + AAC, and hands you a download. There is no account, no queue, no dashboard, and no upload step — the file is read from your disk by your own browser and never leaves it.
What it is not
- Not a batch tool. One file at a time, on purpose: a queue means several decoders and hundreds of megabytes of frames in memory, which is exactly what makes browser compressors fall over on phones.
- Not a converter for every container. MP4, MOV, M4V, WEBM and MKV are read; AVI is not, and the page says so instead of failing halfway through.
- Not a phone tool. iPhone and iPad can run it from iOS 16.4 onwards, but a phone encodes several times slower than a laptop, heats up, and can have the tab killed for memory — long clips belong on a computer. Older iOS versions expose no encoder at all, and the page says so instead of failing halfway.
- Not a cloud service. There is no server in the compression path.
How the encoding works
Decoding and encoding go through WebCodecs, the browser API for exactly this. Container parsing and MP4 muxing come from Mediabunny, which ships under MPL-2.0 and is vendored into this site rather than loaded from a CDN. If a file already fits the target, it is not re-encoded: MP4 comes back untouched, and MKV or MOV with H.264 + AAC is repackaged into MP4 in a fraction of a second with the streams copied.
Who runs it
Clipunder is an independent one-person project. It is not affiliated with Discord. Questions, bug reports, complaints about a bad encode: [email protected].