---
title: "Chrome 'alarms' permission & background service workers in Manifest V3."
description: "What does the 'alarms' permission do in Chrome extensions? Understand the difference between event-driven user-triggered extensions and scheduled background polling."
canonical_url: "https://vezz.me/permissions/alarms-and-background/"
type: "pseo-permissions"
category: "permissions"
topic: "Chrome Permission Audit"
intent: "Best for users comparing strictly user-triggered AI reading tools with background-polling browser agents."
---

# Chrome 'alarms' permission & background service workers in Manifest V3.

What does the 'alarms' permission do in Chrome extensions? Understand the difference between event-driven user-triggered extensions and scheduled background polling.

> **Best fit:** Best for users comparing strictly user-triggered AI reading tools with background-polling browser agents.

## Technical Permission Audit

- **Manifest Key:** `alarms`
- **Chrome Install Warning:** None (displays no install-time warning in Chrome)
- **Risk Level:** Lower

```json
{
  "manifest_version": 3,
  "permissions": ["alarms"],
  "background": {
    "service_worker": "background.js"
  }
}
```

### Legitimate Uses
- Waking up a sleeping Manifest V3 service worker on a schedule for legitimate reminder or page-monitoring tools
- Periodically clearing expired local cache entries

### Red Flags to Watch For
- Combining `alarms` with `<all_urls>` and `tabs` to periodically scrape open tabs or ping tracking endpoints every 5 minutes while you aren't using the extension

**How Vezz me handles this:** Vezz me does NOT request the `alarms` permission. Its background service worker sleeps with 0% CPU and 0 RAM usage until you actively press your shortcut.

## Step-by-step workflow

1. **Check whether the service worker sleeps when idle**: In Manifest V3, a well-behaved extension service worker terminates automatically after 30 seconds of inactivity, freeing all memory.
2. **Avoid periodic background polling unless needed**: Unless you specifically installed a price-tracker or uptime monitor, an AI reading extension should never run periodic `chrome.alarms` jobs.

## Why Vezz me uses zero RAM when you aren't asking a question

Browser sluggishness usually comes from extensions that keep background timers and heavy DOM observers running 24/7.

- No `alarms` permission—Vezz me never wakes up on a timer in the background
- Service worker wakes up only when you press `Ctrl+Shift+X` (or open the settings popup) and goes right back to sleep afterward

## Frequently asked questions

### How can I check if an extension is running in the background right now?

Press Shift+Escape in Chrome (or open Chrome's Window -> Task Manager) to see live CPU and memory usage for every active extension.

## Related guides

- [HARPA AI alternative](https://vezz.me/compare/harpa-ai-alternative/): Compare background automation agents with user-triggered reading.
- [Master permission checker](https://vezz.me/ai-chrome-extension-permission-checker/): Review all Chrome extension permissions.