How browser screen recording works
Modern desktop browsers have a built-in way to share a screen, called getDisplayMedia. It is the same feature video-call sites use when you “present”. When you click Start, your browser (not this website) shows a window where you choose what to share: a whole screen, one app window, or a single browser tab. The website only receives what you pick, and only until you stop.
The tool then hands that video, plus any audio you allowed, to MediaRecorder, which compresses it as it records, usually as VP9 or VP8 in a WebM file, or H.264 in an MP4 file where the browser supports it. If you turn on the webcam, the screen and a rounded webcam bubble are drawn together on a canvas thirty times a second, and that canvas is what gets recorded. Microphone and screen audio are mixed into one soundtrack with the Web Audio API.
Everything stays in your browser. The finished video is kept in the page until you download it.
What each option does
| Option | What it records | Notes |
|---|---|---|
| Screen or tab audio | Sound from the shared tab or the whole system | Chrome and Edge only; tick “Share audio” in the sharing window |
| Microphone | Your voice | Noise suppression and echo cancellation are switched on |
| Webcam in a corner | Your face, in a bubble | Choose the corner and size; the bubble is part of the video |
| Countdown | 3 or 5 seconds before recording starts | Time to switch to the right window |
| Quality | Video bitrate | Higher means sharper text in fast-moving scenes, and bigger files |
How big will the recording be?
At the Standard setting (2.5 Mbps video plus 128 kbps audio), one minute is about (2,500,000 + 128,000) × 60 ÷ 8 = 19.7 million bytes, roughly 19 MB. A 10-minute tutorial is about 190 MB. Screens that barely change, such as slides or a code editor, often come out smaller, because the encoder spends few bits on unchanged areas.
Worked example: a 5-minute bug report
- Tick Record my microphone, untick screen audio, and leave the countdown at 3 seconds.
- Click Start recording, choose the browser tab with the bug, and click Share.
- Talk through the steps while you reproduce the problem. Pause while you look something up.
- Press Stop. At Standard quality, five minutes is about 95 MB.
- Cut the dead time at the start with Trim Video, then shrink it for a ticket attachment with the Video Compressor, for example to 720p.
Tips for clear recordings
- Share a tab or a window rather than the whole screen to keep notifications and other apps out of the video.
- Use a larger font size in editors and terminals. Text that is readable on your screen can blur after compression, especially at lower quality.
- Turn on Do Not Disturb before recording to avoid pop-up notifications.
- Check your microphone first with the Voice Recorder, which has a live level meter.
- For a looping clip of a short interaction, record it here and turn the best moment into a GIF with Video to GIF.
- Need MP4? If your browser only records WebM, convert it with the Video Converter.
Browser support and permissions
Screen recording works in Chrome, Edge, Opera and Firefox on Windows, macOS, Linux and ChromeOS, and in Safari 14.1 or newer on a Mac. Phones and tablets do not allow websites to capture the screen, so use your device’s built-in recorder there.
On macOS, the first time you record you may need to allow your browser under System Settings → Privacy & Security → Screen Recording, then restart the browser. If sharing is cancelled or blocked, the tool explains what happened and how to fix it.