A free WebM to MP4 converter that turns WebM videos into H.264 MP4s in your browser, with nothing uploaded.
Drop your WebM videos and get MP4s that play everywhere. It all happens in this browser.
Your videos
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Re-encoded to H.264 and AAC (VP9 and Opus for WebM), the codecs every player takes, looking the same.
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Add a video to convert.
Everything happens in this browser, with its own video encoders, so your videos never leave your computer. There's no size limit but your computer's memory.
This free WebM to MP4 converter turns WebM videos into MP4s that play on every phone, player and site, in your browser.
WebM is the web's own format, and screen recordings made in a browser are often WebM. Some apps and sites won't take it, and nothing is uploaded here.
Here's why a WebM gets re-encoded, how long it takes, and how it compares with CloudConvert.
TL;DRKey takeaways
What is a WebM to MP4 converter?
A WebM to MP4 converter turns a WebM video, the web's open format, into an MP4, the format everything plays.
WebM holds VP8, VP9 or AV1 video and Opus or Vorbis sound. MP4 players expect H.264 and AAC, so the converter re-encodes both.
Why WebM gets re-encoded
A MOV or an MKV can often be copied into an MP4 as it is. A WebM's VP9 video can't be, since MP4 players, editors and sites expect H.264.
So the converter decodes each frame and encodes it again with your browser's H.264 encoder. The sound goes from Opus to AAC the same way.
Compared with CloudConvert
I ran the same 10-second files through this converter and through CloudConvert, a popular online converter, on September 30, 2026. The score is how alike the result looks to the original, where 1 is identical:
- This converter
- About 1 s, score 0.992
- CloudConvert
- 2.8 s with the upload, score 0.991
CloudConvert's servers re-encode with x264, the best H.264 encoder, so its files came out about a quarter smaller at a similar score. This converter uses your device's own encoder, copies when it can, and never uploads your video.
Nothing is uploaded
Most online converters send your video to their server and send back the result. This one converts in your browser, with the video encoders built into it.
So your video never leaves your computer, there's no upload to wait for, and there's no size limit but your computer's memory.
Who is the WebM to MP4 converter for?
It's for anyone with a WebM that won't open:
- Video resizer – creators posting one video to TikTok, Reels and YouTube
- Video caption generator – anyone adding captions before posting
- Screen recorder – people recording tutorials and demos
- MP4 to MP3 converter – podcasters turning video into an audio feed
Support teams use it to send screen recordings to customers.
More free video tools
Here are my other video converters, and two for what comes next:
- Video converter – any video to MP4, WebM, MOV or GIF
- Compress video – smaller videos, or a size you set
- MOV to MP4 – iPhone and Mac videos that play everywhere
- MKV to MP4 – OBS recordings, instantly
- Video to GIF – a short loop for chats and slides
- GIF to MP4 – a GIF as a video, a fraction of the size
- Video resizer – any video in TikTok, Reels or YouTube's size
- MP4 to MP3 converter – just a video's sound
They're all free, in your browser, with no watermark.
WebM to MP4 converter FAQs
Questions about the webM to MP4 converter? Here's what to know.
A WebM to MP4 converter turns a WebM video into an MP4, the format everything plays.
It re-encodes the video to H.264 and the sound to AAC.
Some players, editors and sites don't take WebM's VP9 video.
Converting it to MP4 fixes that.
A little, since the video is re-encoded.
In my test, it scored 0.992 for looking like the original, where 1 is identical.
Yes, the WebM to MP4 converter is free, with no account, no watermark and no limit on files.
It runs in your browser, so it costs nothing to run.
No, the WebM to MP4 converter converts your videos in your browser.
They never leave your computer.
I did.
I'm Navid Moazzez, and the WebM to MP4 converter is one of my free tools on navid.me.
Read more about me.
Navid Moazzez
AI business strategist & AI OS builder
Navid Moazzez helps creators and founders master AI and build their own AI Operating System (AI OS) to automate their business and life.
Navid.me is reader-supported. When you buy through links on this site, I may earn an affiliate commission. Learn more.
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