Convert WebM to MP4 free: no sign-up, no upload
Convert WebM to MP4 free. There is no sign-up or login, no watermark, and nothing is uploaded, because your files never leave your browser. It turns a WebM video into an MP4 that opens in the editors, phones and players that do not handle WebM.
WebM comes from the web: browser screen recordings, downloaded web clips and some chat exports are often saved this way. Many video editors, older TVs and some Apple devices handle it poorly or not at all, so people convert it to MP4.
WebM usually carries VP8 or VP9 video, and MP4 normally uses H.264, so the video has to be re-encoded rather than just repackaged. Depending on your browser, this pair may need a one-time engine download before the first conversion. Re-encoding is heavy, so long or high-resolution videos are slow.
- Free
- No sign-up
- Never uploaded
- No watermark
Your files are converted on your device and never uploaded.
How to convert
- Drag your WebM files onto the page, or choose them with the file picker.
- Pick MP4 as the target format.
- Review the video options shown for MP4 and keep the original resolution unless you need a smaller file.
- Press Convert and wait for each file to finish.
- Download a single MP4 file, or take several results together as one ZIP.
Features
- Converts WebM video to MP4
- Fixes playback in editors, TVs and Apple devices
- Keeps picture and sound together
- Batch convert several videos
- Download one file or a ZIP of all results
- No watermark, no sign-up, no upload
- May use a one-time engine download, depending on your browser
Supported formats
About the formats
About WebM
WebM is an open container made for the web, usually holding VP8 or VP9 video with Vorbis or Opus audio. It plays well in browsers but has patchy support outside them.
About MP4
MP4 with H.264 video and AAC audio is the format almost everything can play: phones, TVs, editors, social sites and messaging apps.
WebM vs MP4
WebM is open and efficient in browsers. MP4 is the safer choice for sharing and editing. The change involves new video encoding, so a small quality loss is possible and the file may be larger or smaller depending on settings.
Privacy: how it works
- Your videos stay on your device. The page reads each file with the browser's file API, converts it with code running in the tab, and hands the result back as a download. No upload happens, so there is no copy of your file on our servers to protect, delete or leak.
- There is nothing to sign up for and no login. The converter does not ask for an email address, and it does not need to know who you are to do its job.
- Some conversions use a WebAssembly engine that your browser downloads once, the first time you need it. Only the engine is fetched, never your file, and the page shows the approximate size before it starts. Your browser caches it, so later conversions skip the download.
- You can check the claim yourself: open your browser developer tools, watch the Network tab while a file converts, and you will see no request that carries your file.
- Screen recordings often show private windows and messages. They are processed in the tab only. Depending on your browser, this pair may need a one-time engine download (about 31 MB) before the first conversion. The engine is cached by your browser, and your file is never part of that download.
Tips
- If you only need to play the clip in a browser, you may not need to convert it at all.
- Convert a short clip first to check quality and size.
- Long screen recordings are heavy, so convert them on a computer if you can.
- Close other tabs while converting to free memory.
- Keep the WebM until the MP4 has been checked.
- If the sound is missing, the recording may not have had any audio track.
Frequently asked questions
Is it really free?
Yes. There is no price, no trial, no credit card and no watermark added to your results. Ulkaa Tool does the conversion with your own device, so there is no server bill to pass on to you.
Are my files uploaded?
No. Your videos are read and converted inside your browser and are never sent to Ulkaa or to anyone else. The result is created on your device and you save it from there. Some conversions load a small conversion engine the first time you use them. That download is the only network traffic, it contains no file of yours, and your browser keeps it for next time.
Do I need an account?
No. There is no sign-up and no login. Open the page, add your files and convert. An Ulkaa account is not needed for anything on this tool.
Is there a file size limit?
No limit is set by us. The real limit is your device: the conversion uses your own memory and processor, so very large files can be slow or fail on a weak phone or an older computer. Close other heavy tabs and convert videos one at a time if a big batch struggles.