Build a Chrome extension with Manifest V3 and minimal permissions

Prompt

Act as a developer specializing in Chromium-based browser extensions with Manifest V3.

Context:
- What the extension should do: {{purpose}}
- Sites where it works: {{sites}}
- UI and entry points: {{ui}}
- Data it stores and whether it should sync across devices: {{data}}

Deliverables:
1. Architecture: what the service worker, content script and popup or options page do, and how they communicate (chrome.runtime.sendMessage, ports), with a simple diagram.
2. A complete manifest.json with the minimum permissions needed: justify every permission and host_permissions entry; use activeTab or optional_permissions where possible.
3. Code for each file (service worker, content script, popup HTML/CSS/JS, options if needed) in modern JavaScript, with no remote code or eval, respecting the MV3 content security policy.
4. Persistence with chrome.storage (local or sync depending on {{data}}), keeping in mind that the service worker can stop at any time and keeps no in-memory state.
5. Basic popup accessibility (labels, focus, contrast) and strings ready for translation with _locales.
6. How to test it: load unpacked in chrome://extensions, debug the service worker and content script, and test cases.
7. A Chrome Web Store publishing checklist: permission use justification, privacy policy if it handles data, screenshots and icons.

Constraints:
- No data collection or tracking the user did not ask for; if the extension handles personal data, state what must be disclosed in the privacy policy.
- If an API may differ between versions, mark it [VERIFY in the Chrome Extensions docs].
- If it is unclear what the extension should do on each site, ask me first.

Format: numbered sections, a file tree and one code block per file.

How to use it

Usage example

Sample output

{
  "manifest_version": 3,
  "name": "__MSG_extName__",
  "version": "1.0.0",
  "default_locale": "en",
  "action": { "default_popup": "popup.html", "default_title": "__MSG_saveTitle__" },
  "permissions": ["activeTab", "storage"]
}

const list = document.querySelector('#list');

async function render() {
  const { links = [] } = await chrome.storage.sync.get('links');
  list.replaceChildren(...links.map(({ title, url }) => {
    const a = Object.assign(document.createElement('a'), { href: url, textContent: title, target: '_blank' });
    const li = document.createElement('li');
    li.append(a);                          // textContent: never innerHTML with page data
    return li;
  }));
}

document.querySelector('#save').addEventListener('click', async () => {
  const [tab] = await chrome.tabs.query({ active: true, currentWindow: true });
  if (!tab?.url) return;
  const { links = [] } = await chrome.storage.sync.get('links');
  if (!links.some((l) => l.url === tab.url)) {
    links.unshift({ title: tab.title || tab.url, url: tab.url, savedAt: Date.now() });
    await chrome.storage.sync.set({ links });
  }
  render();
});

render();

Key facts

Category

Programming & development · Plugins

Output type

Code

Level

Intermediate

Designed for

ChatGPT, Claude, Gemini and Microsoft Copilot

Verified in

Pending editorial verification

Variables

Purpose, Sites, UI and Data and sync

Language

English

Price

Free, no sign-up

Updated

Nov 7, 2026

Frequently asked questions