Examine source code of DeCaptcha

{
  "description": "Decoder for Completely Automated Public Turing test to tell Computers and Humans Apart",
  "manifest_version": 2,
  "name": "DeCaptcha",
  "version": "0.2resigned1",
  "homepage_url": "https://github.com/itsyashkothari",
  "icons": {
    "48": "icons/icon.png"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_popup": "popup/popup.html",
    "default_icon": {
      "48": "icons/icon.png"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "https://webmail.iitg.ernet.in/src/login.php",
        "https://webmail.iitg.ac.in/src/login.php"
      ],
      "js": [
        "filler.js"
      ]
    }
  ],
  "permissions": [
    "*://developer.mozilla.org/*",
    "webRequest",
    "https://yashkothari.in/api/captcha"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{5a925cc6-28e3-4703-a9d6-8280d44ea40c}"
    }
  }
}