Caffeine - Keep Awake от Chandler Stimson

This extension prevents your operating system from entering hibernate or sleep mode by offering two levels of operation:

1. "Display" level: It prevents single or multiple monitors from dimming or displaying screensavers.
2. "System" level: It prevents the entire system from entering the power-saving state.

Key features of the extension include:
1. Operation on display or system level.
2. Ability to keep the system awake for a specified period (ranging from 5 minutes to 24 hours) and then allow it to sleep.
3. Capability to keep the system awake while downloading a file, ensuring uninterrupted downloads even when you're not actively present. The system will transition to the idle state once the download is complete.

The extension provides an inactive toolbar button. Click the button once to activate the "keep awake" state and prevent the system from sleeping. Clicking the button again will release the system back to its default state. To change the level of operation, use the right-click context menu options. When the extension is disabled, it does not alter your computer's power settings (PC, Mac, or ChromeOS). However, if enabled, the extension overrides these settings and prevents the system from entering sleep mode.

Notes:
The ability of this extension to prevent your computer from going into sleep mode when the lid is closed may vary based on the operating system. Some operating systems allow background activities even when the lid is closed, while others do not. For example, older Chromebooks suspend all activities when the lid is closed.

Here are some use cases for this extension:
1. Ensuring uninterrupted network connections during an ongoing download.
2. Keeping the screen active during a presentation, even if you're not actively using the mousepad.
3. Preventing the screen from dimming while reading an e-book or PDF.
4. Temporarily keeping your computer awake without modifying the power settings of your operating system.