Examine source code of Likilter

{
  "manifest_version": 2,
  "name": "Likilter",
  "description": "Social Media Filter for Likes, Following and Followed by numbers",
  "version": "1.1",
  "content_scripts": [
    {
      "matches": [
        "*://twitter.com/*",
        "*://*.instagram.com/*"
      ],
      "js": [
        "filters.js"
      ]
    }
  ]
}