Convert WebM to MP4
Free, no sign-up, and your files never leave your device.
Drop your files here
Choose filesNothing is uploaded: everything happens in your browser
The video is processed by your device: allow a few seconds for a format change, longer for compression.
Screen recordings, videos downloaded from the web and many browser exports are in WebM, which iPhones, editing software and some social networks handle poorly. The conversion re-encodes the video to H.264 and the audio to AAC, the pair every device plays.
How to convert WebM to MP4
- 1Drop your WebM files in the box, or click to pick them. You can add several at once.
- 2MP4 is already selected. Open the settings if you want to change the quality, the size or the background.
- 3Download each file, or everything at once as a .zip. Nothing was uploaded: the conversion happened on your device.
The formats
WebM
The web's open video format, in VP9 or AV1 with Opus audio. It is light and plays in Chrome, Firefox and Edge, but less well on iPhones, in editing software and on some social networks.
MP4
The universal video format. In H.264 with AAC audio, it plays on every phone, computer, TV and social network. It is the format to aim for when you do not know where the video will be watched.
Your files stay with you
The conversion runs in your browser, with your device's decoders. No file is uploaded, no copy is kept, and nobody but you sees your photos or videos. You can check it in the Network tab of your browser's developer tools: none of your files goes out.
Frequently asked questions
Why does the conversion take time?
WebM is VP9 or AV1, the target MP4 is H.264: every frame is decoded and re-encoded by your device. A computer is faster than a phone.
Is the audio kept?
Yes, the WebM's Opus track is re-encoded to AAC, the standard audio of MP4.
Is the converter really free?
Yes, with no sign-up, no watermark and no limit on the number of files. The conversion runs on your device and costs us nothing, so there is nothing to charge you for.
Are my files sent anywhere?
No. They are read and converted in your browser, then saved straight to your device. No server receives them.
Is there a maximum size?
The limit is your device's memory. Photos and audio files go through without trouble; for a video of several gigabytes, a computer does better than a phone.
Does it work on a phone?
Yes, on iPhone and Android, in Safari, Chrome or Firefox. For video, an up-to-date browser is needed: it provides the decoders being used.
What next, with AI
Sharpen a video with AI
A camcorder shot 480 pixels wide, enlarged to 1080p by both video upscalers side by side. The full workflow, no account needed.
Open the tool