Why is the first run slower?

This tool needs a processing engine that is downloaded once and then cached: ffmpeg.wasm: about 30 MB, fetched once from the jsDelivr CDN and cached by your browser. Only the engine is downloaded. Your file never leaves your device.

Are my files uploaded?

No. This tool runs entirely in your browser tab. Files are read from your disk into memory and the result is generated locally.

Is it free? Are there limits or watermarks?

Free and open source (MIT). There are no file-size caps, daily quotas, accounts or watermarks.

Does it work offline?

Yes, once the page (and any engine it needs) has loaded, it keeps working without a connection thanks to the service worker cache.

Home / Video / Video Converter

Video Converter

Convert between MP4, WEBM, MOV, MKV and AVI.

Free, no uploads, no sign-up. Runs 100% in your browser.

How Video Converter works

Video Converter runs entirely in your browser. Convert between MP4, WEBM, MOV, MKV and AVI. Under the hood it uses ffmpeg.wasm (the FFmpeg media toolkit compiled to WebAssembly (single-threaded core)). Your files are read into this tab’s memory, processed on your own CPU, and handed back to you as a download. Nothing is sent to a server.

Input: MP4, WEBM, MOV, MKV, AVI.

How to use Video Converter

Drop a video onto Video Converter.
The first run downloads the ffmpeg engine (about 30 MB, once).
Set your range, format or quality options.
Process it (progress is shown live), then download.

Tips

Shorter clips and lower resolutions process much faster.
Processing speed depends on your CPU; plug in laptops for long jobs.
Keep the tab in the foreground while encoding.

Video Converter FAQ

Why is the first run slower?: This tool needs a processing engine that is downloaded once and then cached: ffmpeg.wasm: about 30 MB, fetched once from the jsDelivr CDN and cached by your browser. Only the engine is downloaded. Your file never leaves your device.
Are my files uploaded?: No. This tool runs entirely in your browser tab. Files are read from your disk into memory and the result is generated locally.
Is it free? Are there limits or watermarks?: Free and open source (MIT). There are no file-size caps, daily quotas, accounts or watermarks.
Does it work offline?: Yes, once the page (and any engine it needs) has loaded, it keeps working without a connection thanks to the service worker cache.

Related tools

Video Trimmer: Trim and cut clips with a visual timeline, no re-upload.
Video Compressor: Compress videos with quality presets and target resolution.
Screen Recorder: Record screen + webcam bubble with mic and system audio.
Crop Video: Crop a video visually with aspect presets for Reels, Shorts and TikTok (9:16), square (1:1) and portrait (4:5).