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Online video converter - MP4, WebM, MOV, MKV for free

Convert a video to another format right in your browser. The file is not uploaded anywhere - your own device does the encoding, often with hardware acceleration.

  • Free
  • No sign-up
  • Private
  • Runs locally

Drag & drop files here

or click to choose from your device

MP4, MOV, WebM, MKV · the file stays on your device

How to convert a video

  1. 1.

    Choose a file

    Drop a video (MP4, MOV, WebM, MKV) onto the area above or click to select it.

  2. 2.

    Set format and quality

    Pick the output format, optionally limit the resolution to 1080p, 720p or 480p and choose the quality.

  3. 3.

    Convert

    Click Convert. Progress is shown on the bar and you can cancel at any time.

  4. 4.

    Download

    Preview the result and download it. You can compare its size with the original.

Which video format should I choose?

  • MP4 (H.264 + AAC) - the most compatible format: phones, TVs, social media, editors.
  • WebM (VP9/VP8/AV1 + Opus) - open format for websites, usually smaller than MP4 at similar quality.
  • MOV - Apple QuickTime container, used by iPhone and Mac editing.
  • MKV - flexible container for archiving with multiple audio and subtitle tracks.

If unsure, choose MP4.

How does in-browser conversion work?

The tool uses the browser's WebCodecs decoders and encoders. Encoding is fast and no file is uploaded. The codec is chosen automatically for your browser: H.264 for MP4 when available, otherwise VP9 or AV1; VP9 or VP8 for WebM. Browsers without a licensed H.264 encoder will be told so, and WebM is suggested.

How much will the file size change?

Size depends mainly on resolution and quality. A two-minute 1080p clip saved at High quality is typically 25-60 MB. Limiting the resolution to 720p cuts the pixel count by 56%, which usually makes the file 40-50% smaller. Every re-encode loses a little quality, so keep the original.

GoalResolutionQualityApprox. per minute
Archive, further editingkeepHighest / High60-200 MB
YouTube, social mediamax 1080pHigh30-60 MB
Messaging, emailmax 720pMedium8-20 MB
Quick previewmax 480pLow3-8 MB

Common problems and fixes

  • “The file cannot be read” - your browser has no decoder for the codec inside (often HEVC on Windows or Linux, or old AVI codecs). Try Safari or Chrome on a Mac.
  • The result is bigger than the original - the source was already heavily compressed. Choose Medium quality or a lower resolution.
  • No sound in the output - the browser lacks an AAC encoder for MP4/MOV. Pick WebM, which uses Opus audio.
  • Conversion is slow - VP9 and AV1 are often encoded in software. H.264 in MP4 is usually fastest thanks to hardware acceleration.
  • iPhone MOV will not play on Windows - it is usually HEVC. Converting to MP4 with H.264 fixes it.

Frequently asked questions

Is the converter free and private?

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Yes. It is free with no sign-up, and the video is processed entirely in your browser.

Why can't I produce MP4 in my browser?

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Some browsers (e.g. Chromium on Linux) lack an H.264 encoder. The tool then uses VP9/AV1 in MP4 if available or suggests WebM.

Will the quality drop?

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Re-encoding always causes a small loss, but at High or Highest quality it is rarely visible.

Is audio kept?

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Yes, audio is re-encoded to AAC or Opus depending on the format. If the browser lacks an audio encoder you will be warned.

Which files can I open?

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MP4, M4V, MOV, WebM and MKV. Whether a file opens also depends on the codec inside - your browser must be able to decode it (H.264, VP9, AV1 and, in some browsers, HEVC).

How long does a conversion take?

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With hardware H.264 encoding it is often faster than the video plays. Software encoding (VP9, AV1) can take several times the video length. You can cancel at any time.

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