Video Converter
Convert MP4, WebM, MOV, MKV and AVI videos to MP4 (H.264) or WebM (VP9) right in your browser. No upload, no watermark.
Quick answer: Pick a video (MP4, WebM, MOV, MKV or AVI), choose MP4 (H.264/AAC) or WebM (VP9/Opus) and a quality preset, and we transcode it in your browser with ffmpeg.wasm — nothing is uploaded.
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Frequently asked questions
- Is my video uploaded anywhere?
- No — the entire conversion runs in your browser using ffmpeg compiled to WebAssembly. Your file stays on your device and the tool works offline after the page loads.
- Which input formats can I convert?
- MP4, WebM, MOV, MKV and AVI are supported inputs. As long as your browser can decode the source codec, the converter can read it.
- Which output formats do you offer?
- MP4 (H.264 video + AAC audio) for the broadest device and social-platform compatibility, and WebM (VP9 video + Opus audio) for smaller, royalty-free open-format files.
- What do the quality presets do?
- They set the encoder's constant-rate-factor: 'high' keeps more detail at a larger size, 'small' compresses harder for a smaller file, and 'balanced' sits in between. There's no single 'best' — it depends on your size vs quality needs.
- Why is conversion slower than a desktop app?
- WebAssembly runs a bit slower than a native ffmpeg build, and browsers cap CPU threads. For a short clip it's seconds; for a long HD video it can take a few minutes.
- How big a file can I convert?
- Up to 500 MB. Transcoding happens in memory, so very large files may exhaust RAM on low-memory devices — we warn you when we detect a constrained environment.
- Will converting lose quality?
- Any re-encode is lossy by nature, but at the 'high' preset the loss is usually imperceptible. Converting between lossy formats repeatedly compounds the loss, so convert from your best source when you can.
- Does it keep the audio track?
- Yes — audio is re-encoded to AAC (for MP4) or Opus (for WebM) and stays in sync with the video.
- Can it convert to GIF or extract audio?
- Not here — use our Video to GIF tool for animated GIFs, or Extract Audio from Video to pull out an MP3/audio track.
- Why did my MKV fail to load?
- Some MKV files use codecs the browser can't decode (e.g. certain HEVC or AC-3 variants). Try a different source, or re-mux the file with a desktop tool first.