A walkthrough for a colleague, a bug you can show but not explain, a voice note, a lecture. Choose what to capture, press Record, press Stop, and the file is yours. The recording services do the same thing and keep a copy of your screen on their servers; this one encodes in the browser and hands you the file.
It uses the browser's own recorder. The stream is encoded as it is captured, as WebM in Chrome, Edge and Firefox and MP4 in Safari, and kept in memory until you stop. A ten-minute screen recording is a few hundred megabytes at most.
The browser asks, every time. The picker for the screen, and the permission for the camera and microphone, are the browser's; this page cannot record anything you have not just chosen, and ending the share from the browser's own bar stops the recording.
System sound is the browser's call. Chrome and Edge can capture a tab's audio, and on Windows the whole system's, when you tick the box in their picker. Firefox and Safari do not offer it; you get the microphone.
It does not edit. For trimming an audio recording, SNIP. For video, save the file and use an editor; every editor opens WebM and MP4.
Nothing leaves this tab. No frame and no sample goes anywhere. With a folder connected, the file is filed under Sovereign Suite/REEL.
The microphone and the camera, yes. Screen recording is not offered to web pages on iPhone or Android; use the phone's own screen recorder for that.
WebM is what Chrome, Edge and Firefox write natively; Safari writes MP4. Both play in every current browser and open in every editor. Converting is a job for an editor, not for the page that recorded it.
As long as the browser's memory allows: an hour of screen at a modest bitrate is a couple of gigabytes, which a computer holds and a phone may not. For anything long, stop and save in parts.
No. Open the network tab in your browser's developer tools and record for a minute; nothing goes out.