Does my video get uploaded anywhere?

No. Every operation runs in your browser via WebCodecs and mediabunny. Open the network tab while you convert — you won't see a single byte of your file leave the device.

Which containers and codecs are supported?

Containers in/out: MP4, WebM, MOV, MKV for video; MP3, WAV, AAC, FLAC and Ogg for audio. Video encoding uses H.264 for MP4/MOV and VP9 for WebM/MKV; audio uses AAC, Opus, MP3, FLAC or Vorbis depending on the container. All of these are handled natively by WebCodecs in modern Chromium and Firefox.

Why is converting slower than ffmpeg in a terminal?

Browsers expose hardware video encoders through WebCodecs, but they cap concurrency and don't allow shared memory across origins without a site-wide isolation flag (COOP/COEP) that breaks third-party embeds. We trade a little speed for keeping the rest of the site fast and ad-network friendly. For typical clips up to a few minutes, conversion completes in seconds.

What happens if WebCodecs can't decode my file?

You'll get an error explaining the codec isn't supported in your browser. Most real-world MP4/WebM/MOV/MKV files work. Exotic codecs (e.g. ProRes 4444, AV1 in older browsers) may not — try converting them in a desktop tool first, then come back.

How does Video → GIF work?

Frames are decoded with WebCodecs at the fps you pick, scaled to the target width, then encoded into an animated GIF using gifenc. The encoder runs a fast nearest-neighbor color quantizer per frame — output is great for screen recordings and flat graphics, less ideal for noisy photographic video.

Does it work offline?

Yes. mediabunny is pure JavaScript with zero dependencies and no WASM blobs — once the page is in the browser cache, the toolkit works without an internet connection.

tools / audio-video

Audio & video tools.

Convert between MP4, WebM, MOV and MKV. Trim, compress, extract audio, make GIFs, grab frames, merge clips — all running locally in your browser through WebCodecs. Nothing uploads.

Convert between MP4, WebM, MOV and MKV. Uses WebCodecs — no upload, no server.

Drop a video here

● Stays on your device. Nothing is uploaded.

MP4 · WebM · MOV · MKV

How it works

01 Pick a mode. The tab bar lists seven operations: convert, trim, extract audio, video to GIF, compress, frames, merge.
02 Drop a file. Drag and drop, or click. Metadata reads instantly. Powered by mediabunny over WebCodecs — no WASM blob to download, no server round trips.
03 Configure & download. Tune the options for the selected mode, then run. Encoding uses your platform's hardware video encoders where available.

FAQ

Does my video get uploaded anywhere?: No. Every operation runs in your browser via WebCodecs and mediabunny. Open the network tab while you convert — you won't see a single byte of your file leave the device.
Which containers and codecs are supported?: Containers in/out: MP4, WebM, MOV, MKV for video; MP3, WAV, AAC, FLAC and Ogg for audio. Video encoding uses H.264 for MP4/MOV and VP9 for WebM/MKV; audio uses AAC, Opus, MP3, FLAC or Vorbis depending on the container. All of these are handled natively by WebCodecs in modern Chromium and Firefox.
Why is converting slower than ffmpeg in a terminal?: Browsers expose hardware video encoders through WebCodecs, but they cap concurrency and don't allow shared memory across origins without a site-wide isolation flag (COOP/COEP) that breaks third-party embeds. We trade a little speed for keeping the rest of the site fast and ad-network friendly. For typical clips up to a few minutes, conversion completes in seconds.
What happens if WebCodecs can't decode my file?: You'll get an error explaining the codec isn't supported in your browser. Most real-world MP4/WebM/MOV/MKV files work. Exotic codecs (e.g. ProRes 4444, AV1 in older browsers) may not — try converting them in a desktop tool first, then come back.
How does Video → GIF work?: Frames are decoded with WebCodecs at the fps you pick, scaled to the target width, then encoded into an animated GIF using gifenc. The encoder runs a fast nearest-neighbor color quantizer per frame — output is great for screen recordings and flat graphics, less ideal for noisy photographic video.
Does it work offline?: Yes. mediabunny is pure JavaScript with zero dependencies and no WASM blobs — once the page is in the browser cache, the toolkit works without an internet connection.