cdnjs is a free distributed JS library delivery service.
Cloudflare is a web-infrastructure and website-security company, providing content-delivery-network services, DDoS mitigation, Internet security, and distributed domain-name-server services.
Emotion is a library designed for writing CSS styles with JavaScript.
Google Tag Manager is a tag management system (TMS) that allows you to quickly and easily update measurement codes and related code fragments collectively known as tags on your website or mobile app.
Heroku is a cloud platform as a service (PaaS) supporting several programming languages.
HTTP Strict Transport Security (HSTS) informs browsers that the site should only be accessed using HTTPS.