Convert WebM screen recordings, browser captures and downloads into MP4 files that iPhones, PowerPoint and video editors accept. Done on your own device, usually without re-encoding.
✓ No upload — runs in your browser
✓ Batch convert & ZIP download
✓ Free, no sign-up
Drop WEBM files here
or
Free: up to 5 files per batch · Files never leave your device · Paste from the clipboard works too
The free plan converts 5 files per batch. Only the first 5 were added.
Get Pro for US$9 once — unlimited batches and no ads, forever.
1
Waiting…
Private by design
Your files are processed by your own device using WebAssembly and your browser's built-in codecs. Nothing is uploaded, logged or stored.
Fast & offline-ready
No queue, no waiting for a server. Once the page has loaded it even works without a connection.
Works everywhere
Chrome, Edge, Firefox and Safari on Windows, macOS, Linux, Android and iOS. No app to install.
Where WebM files come from
WebM is Google's open container: Matroska slimmed down to VP8, VP9 or AV1 video with Opus or Vorbis audio, all royalty-free. Browsers love it. When a web page records your screen or webcam, Chrome, Edge and Firefox write WebM, which is why the Chromebook screen recorder, Screencastify, countless record-your-screen tools and many support-desk apps hand you a .webm. OBS writes it when set to WebM output, and yt-dlp produces it for VP9 downloads. The format is less loved outside the browser: the iPhone Photos app, iMovie, PowerPoint, Premiere Pro and Final Cut either reject it or need plug-ins, and that is usually the moment people search for a converter.
Usually a container swap, nothing more
The codecs WebM uses are all permitted inside MP4, so in most cases Tinyvert does not decode a single frame. It reads the VP9 (or VP8 or AV1) video and the Opus audio out of the WebM and writes the same compressed data into an MP4 file. That keeps every pixel exactly as recorded, needs no codec support from your browser and finishes in a few seconds for a typical recording. The one exception is older WebMs with Vorbis audio, which MP4 does not accept: the audio is re-encoded to AAC or Opus while the picture is still copied.
When the player wants H.264
A copied MP4 is still a VP9 video wearing an MP4 badge. Browsers, Android and VLC play it happily; some Apple and Microsoft apps, older smart TVs and a few upload forms expect H.264 inside MP4 and will stall. The fix is a deliberate re-encode: set a Max resolution (1080p downwards shrinks larger videos; nothing is ever upscaled) or choose a Quality level, and the video is decoded and encoded again, with H.264 wherever the browser offers it. That takes longer and costs a little quality, so do it only when you need to.
What you get
An .mp4 with the same resolution, frame rate and duration as the recording.
The soundtrack intact, or no soundtrack if the capture was silent.
No subtitle tracks or chapters, which are not carried over.
A per-file progress bar, a ZIP for the whole batch, and a Share button on phones that support it.
Privacy and limits
Screen recordings tend to contain passwords, customer data and unreleased work. Tinyvert never uploads them: the conversion runs inside the browser tab, nothing is stored, and the page keeps working offline after its first visit. Large files are limited by your device's memory. To go the other way, MP4 to WebM re-encodes to VP9; MKV to MP4 handles WebM's bigger sibling; and Compress Video is the better tool when size, not format, is the problem.
How to convert webm to mp4 — step by step
1
Drag your WebM files into the drop zone or click "Choose files"; up to five convert per batch, each starting straight away.
2
For a lossless copy leave the settings alone. If the MP4 must hold H.264, pick a Max resolution or a different Quality before adding the files so the video is re-encoded.
3
Wait for the progress bar; the row then shows the new size and "copied" or "re-encoded".
4
Download each MP4, grab all of them as a ZIP, or Share the result from your phone.
Frequently asked questions
Why did my screen recording come out as WebM?
Browsers record video through the MediaRecorder API, and in Chrome, Edge and Firefox its native output is WebM. The Chromebook screen recorder, Screencastify and most record-your-screen web apps therefore save .webm files, and yt-dlp produces them whenever YouTube serves a VP9 stream.
Does WebM to MP4 lose quality?
Normally not. MP4 can carry VP8, VP9 and AV1 video and Opus audio, which is exactly what WebM contains, so Tinyvert copies the streams rather than re-encoding them. Only WebMs with Vorbis audio have that one track re-encoded to AAC or Opus; the picture is still copied.
The MP4 still will not open in iMovie or PowerPoint. Why?
A copied MP4 still holds VP9 video, and some Apple and Microsoft apps only accept H.264 inside MP4. Pick a Max resolution or a different Quality to force a re-encode; Tinyvert then encodes H.264 wherever your browser can, and the row reports "re-encoded".
Can I convert a WebM with no sound?
Yes. Screen recordings often have no audio track, and the MP4 simply has none either. Nothing is added or invented.
Is there a length or size limit?
No fixed limit. The file is processed in your browser's memory, so large files are limited by your device's memory. Hour-long captures are better handled on a desktop or laptop than on a phone; if one fails, cut it with Trim Video first.
Which browsers are supported?
Chrome, Edge, Brave and Opera on desktop and Android, Safari 17 or newer on Mac and iPhone, and Firefox 130 or newer. Because a copy needs no decoder, the remux works even where the browser cannot play VP9 itself.