Speculation Rules API: Make Page Navigations Instant

Users judge a site in milliseconds. Even a well-optimized page that takes 800ms to load on the next click feels sluggish compared to a navigation that appears instantly. For years the only way to get that “instant” feel was a Single Page Application that hijacked routing in JavaScript — complex to build, heavy to ship, and prone to breaking the back button. The Speculation Rules API gives you the same instant feel on a plain multi-page site, using nothing but a small block of JSON the browser reads natively.

This guide teaches you how to prefetch and prerender the right pages at the right moment, how to tune how aggressively the browser speculates, and how to avoid the real-world traps — double-counted analytics, wasted bandwidth, and accidentally triggering destructive links. By the end you will be able to add near-zero-latency navigation to an existing site without adopting a framework or shipping a router.