Cloudflare is a web-infrastructure and website-security company, providing content-delivery-network services, DDoS mitigation, Internet security, and distributed domain-name-server services.
Fastly is a cloud computing services provider. Fastly's cloud platform provides a content delivery network, Internet security services, load balancing, and video & streaming services.
GitHub Pages is a static site hosting service.
MathJax is a cross-browser JavaScript library that displays mathematical notation in web browsers, using MathML, LaTeX and ASCIIMathML markup.
Planet is a feed aggregator, which creates pages with entries from the original feeds in chronological order, most recent entries first.
Varnish is a reverse caching proxy.