cdnjs is a free distributed JS library delivery service.
Facebook pixel is an analytics tool that allows you to measure the effectiveness of your advertising.
Google Analytics is a free web analytics service that tracks and reports website traffic.
Heroku is a cloud platform as a service (PaaS) supporting several programming languages.
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.
Open Graph is a protocol that is used to integrate any web page into the social graph.