Examine source code of DuoKB

{
  "description": "Changes input for Duolingo without need of switching keyboard layouts.",
  "manifest_version": 2,
  "name": "DuoKB",
  "version": "0.9",
  "homepage_url": "https://github.com/cdberkstresser/DuoKB",
  "icons": {
    "16": "icons/duokb-16.png",
    "32": "icons/duokb-32.png",
    "48": "icons/duokb-48.png",
    "64": "icons/duokb-64.png",
    "96": "icons/duokb-96.png",
    "128": "icons/duokb-128.png"
  },
  "options_ui": {
    "page": "options.html",
    "open_in_tab": false
  },
  "browser_action": {
    "default_icon": "icons/duokb-128.png",
    "default_title": "DuoKB"
  },
  "content_scripts": [
    {
      "matches": [
        "https://*.duolingo.com/*"
      ],
      "js": [
        "duokb.js",
        "translations.js",
        "options.js"
      ]
    }
  ],
  "permissions": [
    "storage"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{3cc0602a-7959-4c83-880f-a659b1ba6d7b}"
    }
  }
}