Video Format Converter
Convert between MP4, WebM, and MOV containers with codec and quality options, all in-browser.
What is Video Converter?
A container and codec converter for video: MP4 for universal playback, WebM for the web, MOV for Apple tools, and legacy MPEG-4 for old devices.
How it works
Your file is demuxed and re-encoded by the bundled ffmpeg engine, which picks the encoder you choose (libx264, mpeg4, libvpx, libvpx-vp9) and the matching audio encoder (AAC, Vorbis or Opus). Resolution and web-optimisation flags are applied in the same pass.
- Load your file. Drag a file onto the drop zone or pick one from your device. It is read locally by the browser and never uploaded.
- Set the options. Adjust the handles, format, quality or threshold controls — the preview updates as you change them.
- Process and download. Run the tool, then download the result. Compare the reported before/after size for compressors and converters.
Examples
A 42 MB podcast episode → 9 MB MP3
Trim the intro, normalise to −16 LUFS, and export at 96 kbps mono — a typical interview lands around a fifth of the original size.
A phone video with the wrong orientation
Rotate 90° and the width/height swap in the output, so it plays upright in every player instead of relying on metadata flags.
Common mistakes
Expecting instant encoders
Video encoding runs in single-threaded WebAssembly, so a clip takes roughly its own length (or a little longer) to re-encode. Stream-copy operations are near-instant by comparison.
Re-encoding when a copy would do
Trimming, removing audio and joining same-codec clips can copy streams without re-encoding — pick the copy option when it is offered to avoid any quality loss.
Ignoring the first-load download
The media engine is about 31 MB and is fetched on first use, then cached. The first conversion on a connection is slower than every later one.
Frequently asked questions
Which codec should I choose?
H.264 in MP4 plays literally everywhere — phones, browsers, TVs and editors. VP9/WebM gives smaller files for the web but encodes more slowly in the browser.
What is fast start?
It moves the MP4 index to the beginning of the file so players can start before the download finishes. Leave it on for anything published on the web.
Can it read MKV or AVI?
Yes — the engine demuxes both, and the output is always one of the modern containers it can mux: MP4, WebM or MOV.