The complete picture

The ultimate guide to preventing screen timeout.

Three real approaches, ranked from least to most permanent — pick based on how often you need this, not just whichever you find first.

Inactive

Pick a duration and hit start.

Duration

1. A browser-based tool (least permanent, zero setup)

What this site does — open a tab, hold the display open for as long as you need, close it when you're done. Nothing to install, nothing to remember to undo, works on machines you don't have admin rights on. The right choice for a one-off need: a presentation, a long download, watching an AI agent finish a task. Start with this option if you're not sure which you need yet.

2. A native command or app (persistent, needs install/access)

Keeps working even if you close the browser, at the cost of needing to install something or have Terminal access:

Mac: the built-in caffeinate Terminal command, or the menu-bar app Amphetamine.
Windows: Microsoft's own PowerToys Awake, a free system-tray utility.
Linux: most desktop environments ship a caffeine or systemd-inhibit equivalent.

3. Change the OS setting directly (most permanent)

The right call if you basically never want this machine to auto-lock/sleep — a desktop that's always plugged in, for instance. Worth remembering this is also the only option that affects system sleep, not just the display — see our note on that distinction on the AI-agent page if you're trying to keep a long background task alive, not just the screen lit.

Windows: Settings → System → Power & sleep.
Mac: System Settings → Lock Screen, and Battery → Options.
Android: Settings → Display → Screen timeout.
iPhone: Settings → Display & Brightness → Auto-Lock.

Full platform-specific guides, each with the working tool built in too: Windows, Mac, Chrome, Android, iPhone.

Methods compared

Method	Setup	Survives closing the browser	Prevents system sleep
This tool	None	No	No
Native command/app	Install once	Yes	Usually
OS setting	One-time change	Yes	Yes