JSDelivr is a free public CDN for open-source projects. It can serve web files directly from the npm registry and GitHub repositories without any configuration.
Modernizr is a JavaScript library that detects the features available in a user's browser.
reCAPTCHA is a free service from Google that helps protect websites from spam and abuse.
Vue.js is an open-source model–view–viewmodel JavaScript framework for building user interfaces and single-page applications.