Ahrefs is an online toolset utilised for search engine optimisation (SEO) and competitor analysis, which permits users to analyse their website's performance, track keyword rankings, identify backlink opportunities, and research competitors' websites, among other features.
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.
Gravatar is a service for providing globally unique avatars.
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.
Varnish is a reverse caching proxy.