Drop in your MP4 files and get WebM files back. Everything runs in your browser: nothing is uploaded, there is no file size limit and you do not need an account.
Accepts: images (PNG, JPG, WebP, GIF, BMP, SVG, ICO, AVIF, HEIC), PDF, Word (.docx), Markdown, HTML, TXT,
spreadsheets (XLSX, XLS, ODS, CSV, TSV), JSON, XML, YAML, and video (MP4, MOV, WebM, MKV) or audio. Video can become GIF (first 15 seconds), WebM or MP4 (recorded in real time, so it takes as long as the video), a still image, or just the audio. Mixed batches are fine.
Add files to begin.
How to convert MP4 to WebM
Drag your MP4 files into the box above, or click it to choose them.
WebM is already selected as the output format.
Press Convert Files, then Download All. Several results arrive as one ZIP.
Why convert MP4 to WebM?
WebM is an open format that suits embedding video on web pages.
MP4 is the most widely supported video format. WebM is an open video format built for the web.
Your files never leave your device
Most online converters upload your files to a server. This one does the work inside your browser, so your MP4 files stay on your computer or phone. That also means no waiting for uploads and no cap on file size.
Good to know
Video is converted by playing it and recording the result, so it takes about as long as the video lasts, and this tab needs to stay open and visible.
WebM recording works in all major browsers; some players may not show the duration of recorded WebM files.
Frequently asked questions
Are my MP4 files uploaded to a server?
No. The conversion runs inside your browser on your own device. Your files are not sent to us or anyone else. Besides loading this page and, for some formats, a small helper library, nothing is downloaded or uploaded while you convert, and you can confirm that in your browser's developer tools (Network tab).
Is there a limit on file size or number of files?
We do not set one. The only limit is your device's memory, so for very large batches (thousands of files, or very big videos) work in several groups.
Do I need to sign up, install anything or accept a watermark?
No. There is no account, no install and no watermark. Open the page, add your files and download the results.
How do I convert many MP4 files at once?
Drag them all in together or pick them in the file chooser. They are converted one after another, and Download All saves the results as one ZIP (a single result downloads directly).
Are there any limitations converting MP4 to WebM?
Video is converted by playing it and recording the result, so it takes about as long as the video lasts, and this tab needs to stay open and visible. WebM recording works in all major browsers; some players may not show the duration of recorded WebM files.