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Convert WebM to MP4
Turn a WebM from a browser or screen recorder into an MP4 your phone and editor can open. Your file is never uploaded — it's processed right here in your browser.
How it works
01. Add your WebM file
Drop or choose your WebM file. Other video formats work too.
02. Leave the rest to us
Nothing to choose. VP8/VP9 video becomes H.264 and Opus audio becomes AAC.
03. Download the MP4
Hit Convert and download your MP4 file when it's ready.
Why convert to MP4?
WebM is the default for browser recordings and web video, but iPhone, the Mac Photos app and many editors can't open it. MP4 opens everywhere.
How the conversion works
VP8 and VP9 aren't widely playable inside MP4, so every frame is re-encoded to H.264. It takes time depending on length and your device.
Frequently asked questions
Why does it take a while?
WebM to MP4 has to change the codec, so every frame is re-encoded. Desktop Chrome and Edge use hardware encoders and are usually faster than real time.
Is my video stored anywhere?
No. The file never leaves your device — it's processed inside this tab with WebCodecs. Close the tab and nothing is left behind.
Is there a file size limit?
Up to 2 GB per file. The result is held in your browser's memory, so on devices with little RAM smaller files are safer.
Which browsers are supported?
Recent Chrome, Edge, Safari and Firefox. Speed depends on your device — desktop Chrome and Edge are usually the fastest.
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Got a long video? Make it many shorts
Shorts Zone finds the best moments in a long video and turns them into captioned vertical shorts in one go. Just like this tool, your video never leaves your device.