Examine source code of Letterboxd Extras

{
  "manifest_version": 2,
  "name": "Letterboxd Extras",
  "description": "Display ratings from other film sites, and other nifty extras, directly on Letterboxd. Fully customizable.",
  "version": "3.20.1",
  "browser_specific_settings": {
    "gecko_android": {
      "strict_min_version": "120.0"
    },
    "gecko": {
      "id": "{9abb0ce4-6348-4119-b97a-3f8116351aca}",
      "strict_min_version": "115.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "browser_action": {
    "default_title": "Letterboxd Extras",
    "default_popup": "options.html?type=action",
    "default_icon": {
      "16": "icon16.png",
      "32": "icon32.png",
      "48": "icon48.png",
      "64": "icon64.png",
      "96": "icon96.png",
      "128": "icon128.png",
      "256": "icon256.png",
      "512": "icon512.png"
    }
  },
  "icons": {
    "16": "icon16.png",
    "32": "icon32.png",
    "48": "icon48.png",
    "64": "icon64.png",
    "96": "icon96.png",
    "128": "icon128.png",
    "256": "icon256.png",
    "512": "icon512.png"
  },
  "options_ui": {
    "page": "options.html",
    "browser_style": true,
    "open_in_tab": true
  },
  "permissions": [
    "https://letterboxd.com/*",
    "https://*.imdb.com/*",
    "https://www.rottentomatoes.com/*",
    "https://www.boxofficemojo.com/*",
    "https://webapp.cinemascore.com/*",
    "https://query.wikidata.org/*",
    "https://www.metacritic.com/*",
    "https://graphql.anilist.co/*",
    "storage",
    "scripting"
  ],
  "optional_permissions": [
    "https://apollo.senscritique.com/*",
    "https://api.mubi.com/*",
    "https://*.filmaffinity.com/*",
    "https://www.allocine.fr/*",
    "https://api.simkl.com/*",
    "https://www.google.com/search*",
    "https://www.doesthedogdie.com/*",
    "https://markuapi.kabk.dev/*",
    "https://kinopoiskapiunofficial.tech/api/*",
    "https://api.douban.com/*",
    "https://api.mydramalist.com/*",
    "https://api.tenrai.org/*"
  ],
  "content_scripts": [
    {
      "matches": [
        "https://letterboxd.com/*"
      ],
      "js": [
        "polyfill.js",
        "additional.js",
        "letterboxd-extras.user.js"
      ],
      "run_at": "document_end"
    }
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "web_accessible_resources": [
    "images/*",
    "options.*"
  ]
}