Video Format Converter

Upload your video, download it as MP4, MOV, or WEBM. Free, no sign-up, runs entirely in your browser.

Whether you got a MOV from an iPhone that your video editor won't accept, or need a WEBM for faster web embedding instead of a heavy MP4, this tool re-encodes the video and audio tracks into your chosen container directly in your browser, keeping the original resolution and framerate, so you get a working file in the format you actually need.

How it works

  1. Upload your video. MP4, MOV, WEBM, MKV, or AVI, up to 300MB.
  2. Choose your target format. MP4, MOV, or WEBM.
  3. Download the converted video. Entirely in your browser — larger videos take a little longer.

Why Stelluna

Frequently Asked Questions

Is it free?
Yes, no account needed.

Does my video get uploaded anywhere?
No, conversion runs entirely in your browser using your device's own video encoder.

Which formats are supported?
Output: MP4, MOV, WEBM. MKV and AVI are also accepted as input, up to 300MB.

Do I need to sign up?
No.

Why do some conversions fail?
Your browser may not support that target format's video encoder — try a different format or an up-to-date Chrome/Edge.

Does converting reduce video quality?
Some quality loss is unavoidable any time video is re-encoded, but the converter targets a high bitrate close to your source file so the difference is generally not noticeable — resolution and framerate are kept the same as the original.

Is my video stored anywhere after I download it?
No. Conversion happens entirely in your browser's memory, so closing the tab or refreshing the page erases both your original file and the converted result — nothing is uploaded or kept.

Which devices and browsers does it work on?
Any modern browser with WebCodecs support — recent versions of Chrome, Edge, Firefox, and Safari, on desktop or mobile. If your browser doesn't support the required APIs, you'll see an error when you try to convert.