Caching feature of browser's Fetch API is one of the most powerful — and most misunderstood — tools in web development. It gives you fine-grained control over how HTTP requests interact with the cache through a single cache option. Used correctly, it can dramatically speed up your app, reduce server load, and improve offline resilience. Used incorrectly, it can serve stale data, confuse users, and cause hard-to-debug issues. Before diving into the options, it's worth understanding what "the cache" actually means here. When your browser makes an HTTP request, it can store the response in a local cache (the HTTP cache , sometimes called the browser cache). On subsequent requests to the same URL, the browser can serve the response directly from this cache instead of going to the network — making the response near-instant and saving bandwidth. Servers communicate caching rules via HTTP response headers like Cache-Control , ETag , Last-Modified etc.…