What is video compression?

Video files are enormous, and most of their size is spent reproducing detail nobody sees. This tool re-encodes your video with the industry-standard H.264 encoder, giving you direct control over the two settings that dominate the size-quality balance: output resolution (240p, 360p, 480p, 720p, or 1080p, with aspect ratio preserved) and CRF — the quality factor, where lower numbers mean better quality and larger files, and a value around 23–28 hits the practical sweet spot for most content. An encoding-speed preset lets you trade processing time for marginally better compression.

The honest expectation to set: this is real re-encoding, not a container trick. Your browser loads the file into an in-memory FFmpeg (WebAssembly) and re-compresses every frame, so a long video takes real time — minutes, not seconds — and very large files need both patience and adequate browser memory. The payoff is usually dramatic: a 1080p recording dropped to 720p can shrink by 70–80% while still looking fine on a phone or in a lecture capture.

Typical uses: getting a screen recording under a learning-platform or email size limit, shrinking phone footage before sharing, and preparing clips for upload platforms that re-compress everything anyway (feeding them a smaller file loses almost nothing visible).

Everything runs locally in your browser — the video is never uploaded, which matters for internal recordings, client footage, or anything confidential. Two tips: compress from the highest-quality source you have, and compress once; re-compressing an already-compressed file visibly degrades it. Audio is re-encoded to AAC, which plays everywhere.