Examine source code of YOURLS shortener

{
  "manifest_version": 2,
  "name": "YOURLS WebExtension",
  "version": "2.5.2",
  "description": "Shorten URLs with your own YOURLS instance",
  "homepage_url": "https://binfalse.de/software/browser-extensions/yourls-firefox-webextension/",
  "applications": {
    "gecko": {
      "id": "yourls-shortener@binfalse.de",
      "strict_min_version": "57.0"
    }
  },
  "icons": {
    "48": "yourls.svg",
    "96": "yourls.svg"
  },
  "permissions": [
    "activeTab",
    "storage",
    "clipboardWrite",
    "contextMenus",
    "http://*/*",
    "https://*/*"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "options_ui": {
    "browser_style": true,
    "page": "options.html"
  },
  "browser_action": {
    "browser_style": true,
    "default_icon": "yourls.svg",
    "default_title": "YOURLS",
    "default_popup": "popup.html"
  }
}