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Useful Chrome extensions flashcards

Choose and manage extensions safely, then learn how Manifest V3 extensions really work inside.

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Beginner friendly, starts from zero
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Useful Chrome extensionsStart from zero · 1 of 12

What is a Chrome , in one plain sentence?

A browser is the app you open websites with, and Chrome is Google's browser. An is a small add-on you put into Chrome to give it a new skill, like saving a whole page as a picture.

Apps are for your phone; are apps for your browser.

All topics

Useful Chrome extensions at a glance

Extensions are small add-ons that give Chrome new skills, and this topic shows how to pick and use them safely.

An extension is like a house guest you give a key to: helpful, but able to enter the rooms you open for it.

Words you will meet

Extension
A small add-on that gives the Chrome browser a new skill
Chrome Web Store
Google's official shop where you get extensions
Permission
Something an extension asks to be allowed to do, like read your pages
Toolbar
The row of buttons beside the address bar where extension icons sit
Incognito
A private window that forgets your history when closed
Manifest V3
The current rule book for how Chrome extensions are built
Malware
Bad software that spies on you or steals from you

The steps

  1. 1. Start from zero (12 cards): What an extension is, why it can see your pages, and the few words you need.
  2. 2. Core basics (14 cards): Install, pin, limit and remove extensions, and read the permission prompt like a pro.
  3. 3. Next steps (15 cards): Site access, shortcuts, choosing well, performance and the sdev tools in real work.
  4. 4. Go deeper (17 cards): Manifest V3 internals: service worker life cycle, messaging, permissions, capture APIs and store review.
All 12 cards in Start from zero
What is a Chrome extension, in one plain sentence?
A browser is the app you open websites with, and Chrome is Google's browser. An extension is a small add-on you put into Chrome to give it a new skill, like saving a whole page as a picture.
What was it like before extensions, and what problem do they solve?
A browser only does common jobs. To save a long page you took many screenshots and joined them by hand; an extension adds one button that does it for you.
Where have you already met an extension without noticing?
A grammar checker underlining words as you type, a coupon finder at checkout, a translate button on a foreign page, or a pop-up offering to fill your password are often extensions.
What everyday thing is an extension like?
Like a house guest you give a key to. A helpful guest makes life easier, but with the key they can walk into every room, so you only hand keys to people you trust.
What are the Chrome Web Store, the toolbar and the puzzle-piece icon?
The Chrome Web Store is Google's official shop for extensions. After you install one, its icon sits under the puzzle-piece icon in the toolbar, the row of buttons beside the address bar.
What is a permission?
A permission is something an extension asks to be allowed to do, such as read the pages you open or see your downloads. Chrome shows this list when you click Add to Chrome.
What do data, server and privacy policy mean here?
Your data is anything about you: pages you visit, what you type, your pictures. A server is a far-away computer run by the extension's maker. A privacy policy is their written promise about your data.
What are Incognito and malware?
Incognito is a private Chrome window that forgets your history when you close it. Malware is bad software that spies, steals or shows unwanted ads; some fake extensions are malware.
What do Manifest V3 and Developer mode mean?
Manifest V3 is the current rule book Chrome uses for how extensions are built; older ones under the old rules no longer run. Developer mode is a switch on the extensions page that shows extra details like errors.
What do you need before you start?
Just Chrome on a laptop or desktop computer, which is where extensions run. Nothing to buy, nothing to set up first.
First tiny win: how do you see every extension you have?
Type chrome://extensions in the address bar and press Enter. The chrome:// start means one of Chrome's own pages, not a website, and it lists every extension with an on/off switch.
What will you be able to do after this topic?
Judge an extension before you install it, read its permission warning, pin, turn off or remove tools, and use free sdev tools for screenshots and screen recordings that stay on your device.
Useful Chrome extensions cheatsheet

Chrome pages

  • chrome://extensions Manage, toggle, see errors
  • chrome://extensions/shortcuts Keyboard shortcuts per extension
  • chrome://settings/safetyCheck Flags harmful or removed extensions
  • chrome://password-manager Built-in passwords and passkeys
  • chrome://policy Policies your company applies
  • chrome://inspect/#service-workers All running service workers

sdev extensions

  • Full Page Screenshot Whole page, visible area or a selected part
  • Hide private info Pick parts to hide before saving
  • Export PNG, JPG, PDF Save the screenshot your way
  • Screen Recorder Tab or screen with camera and mic
  • Cuts and zooms Trim and focus, export up to 4K
  • On-device files Nothing uploaded unless you share

Safety checklist

  • Site access: On click Runs only when you click it
  • Fewest permissions Matches what the feature needs
  • Named developer Real site and contact
  • Privacy practices Store page says what data leaves
  • Recent update Still maintained
  • Remove unused Less risk, less memory

manifest.json (MV3)

  • "manifest_version": 3 Required
  • "background": { "service_worker": "sw.js" } Event-driven background
  • "permissions": ["activeTab", "scripting"] Current tab after a click
  • "optional_host_permissions": ["https://*/*"] Ask for sites later
  • "content_scripts": [{ "matches": [], "js": [] }] Code injected into pages
  • "commands": { "_execute_action": {} } Shortcut that opens the action

Core APIs

  • chrome.storage.session.set({ k }) In-memory state across worker naps
  • chrome.alarms.create('sync', { periodInMinutes: 15 }) Timers that survive sleep
  • chrome.scripting.executeScript({ target: { tabId }, files }) Inject on demand
  • chrome.runtime.sendMessage({ type }) One-off message
  • chrome.tabs.captureVisibleTab() Image of the visible tab
  • chrome.offscreen.createDocument({...}) Hidden page for DOM and media
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