HTTP Strict Transport Security (HSTS) informs browsers that the site should only be accessed using HTTPS.
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.
Optimizely is an experimentation platform that helps developers build and run A/B tests on websites.
Priority Hints exposes a mechanism for developers to signal a relative priority for browsers to consider when fetching resources.
Progressive Web Apps (PWAs) are web apps built and enhanced with modern APIs to deliver enhanced capabilities, reliability, and installability while reaching anyone, anywhere, on any device, all with a single codebase.