Video and Audio Tools
Three of these tools run FFmpeg compiled to WebAssembly inside the page, which is what makes browser-based trimming and conversion possible at all. The engine is roughly 30 MB and is fetched from a public CDN the first time you start an operation, so the first run needs a connection and a moment to warm up.
Screen recording is different: it uses the browser's own recording API and does not need FFmpeg at all.
Tools in Video and Audio Tools
How these tools behave
- The FFmpeg engine is downloaded from unpkg.com on first use. Your media file is not uploaded; only the engine is downloaded.
- Trimming copies the existing streams rather than re-encoding, so cuts land on the nearest keyframe.
- Screen recording asks for the browser's screen-capture permission and produces a WebM file in most browsers.
Frequently asked questions
Why is the first run slow?
The FFmpeg WebAssembly build has to be downloaded and compiled before any work can start. Subsequent runs in the same session reuse it.
Why is my trim slightly off?
The trim copies the video stream without re-encoding it, which is fast and lossless but can only cut at keyframes. The start point moves to the nearest one.
Guides
- What “processed in your browser” really means — Which parts of a browser-based tool touch the network, which do not, and how to check for yourself in DevTools.