About this tool
Cutting a clip, converting a container format, pulling out the soundtrack, or turning a moment into a shareable GIF usually means installing desktop software or uploading footage to a random website. This toolkit runs a real build of FFmpeg compiled to WebAssembly directly in your browser, so video and audio never leave your machine. Trim a clip to an exact start and end time, convert between MP4 and WebM, extract the audio track as MP3, WAV, or M4A, or generate an optimized-palette GIF from any segment — all with a live progress bar while FFmpeg does the work locally. The first operation on a page load takes a few seconds to fetch the FFmpeg engine (a few megabytes, cached by your browser afterward); every run after that starts instantly.
Frequently asked questions
Is my video or audio file uploaded to a server?
No — FFmpeg runs as WebAssembly directly in your browser tab. The file is read locally and never transmitted anywhere.
What file formats can I use as input?
Common containers work well, including MP4, WebM, MOV, MKV, and AVI for video, and MP3, WAV, M4A, and OGG for audio.
How do I specify the start and end time for trimming?
Use minutes:seconds format like 0:05 or 1:30. Leave the end time within your clip's actual length — the diagnostics panel will tell you if it's out of range.
Why does the first conversion take longer than later ones?
The first run on a page load downloads the FFmpeg WebAssembly engine (a few megabytes). Your browser caches it, so subsequent conversions on the same page start immediately.
Is there a file size or length limit?
There's no hard limit we impose, but since processing happens in your browser's memory, very large or long files may be slow or use significant RAM depending on your device.