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Manifest V3 generator

Manifest V3 storage permission

The storage permission unlocks chrome.storage — the extension's own key-value store, with local, session and sync areas. It is the right home for settings and small state: unlike localStorage it is available to the background service worker, survives the worker being stopped, and sync mirrors the data across the user's signed-in browsers.

It produces no install warning, which is why almost every extension declares it. The sync area is quota-limited (about 100 KB in total and 8 KB per item), so anything larger belongs in local; and because the API is asynchronous, a popup that reads settings on open should await the get before rendering rather than assuming a synchronous cache.

Storage at a glance

Manifest key
"permissions": ["storage"]
What it enables
Save the extension's own data, and sync it across the user's signed-in browsers.
Install warning
None — granted silently at install.
Cross-browser API
browser.storage via webextension-polyfill

The manifest that declares it

Manifest with this permission

manifest.json
{
  "manifest_version": 3,
  "name": "my-extension",
  "version": "0.1.0",
  "action": {
    "default_popup": "src/popup.html"
  },
  "background": {
    "service_worker": "src/background.ts",
    "type": "module"
  },
  "permissions": [
    "storage"
  ]
}

This manifest installs with no permission warning.

storage, answered

The longer version is in the guide Manifest V3 permissions: a practical guide.

What does the storage permission do in Manifest V3?
Save the extension's own data, and sync it across the user's signed-in browsers. It is declared as the string "storage" in the manifest's permissions array; the browser grants it at install time, and the extension's service worker, popup and other pages can then call the matching API.
Does storage show an install warning?
No. storage is granted silently — it appears in the manifest but adds nothing to the install prompt. Host permissions and warning-bearing permissions such as tabs or downloads are what change the prompt.
Can I request storage at runtime instead?
Yes. Move it from permissions to optional_permissions and call browser.permissions.request({ permissions: ["storage"] }) from a user gesture when the feature is first used. The manifest generator emits the install-time form; optional grants are an edit to that JSON.

Build the whole manifest

The Chrome extension manifest generator declares every permission with its install warning shown up front, adds the surfaces the browser opens, and validates content-script match patterns before they can reject the whole extension. In the Nodlume workspace the same selection becomes a complete Manifest V3 project with a service worker and a Vite build.

Open the generator

Other Manifest V3 permissions

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