PageSpeed header analyzer

Understanding HTTP Headers for Peak Web Performance

Before you get your score, let's break down what this tool is actually looking at. HTTP headers are the silent workhorses of the web, acting like a digital shipping label for every file your browser requests. They are key-value pairs of metadata sent between the browser and the server that provide crucial instructions on how to handle the content. Getting them right is not a micro-optimization; it is a fundamental requirement for a fast website.

Why Headers are Critical for Speed

Misconfigured headers are a direct cause of poor performance. They instruct browsers to re-download assets that haven't changed, they fail to leverage modern protocols, and they can even block rendering. The goal is to eliminate every unnecessary network request and make each required request as efficient as possible. Headers are your primary tool for this.

The Key Players: What We Analyze

1. Caching Policy

This is the most important performance header. It tells browsers and CDNs how long they are allowed to store a file locally. For static assets like images, CSS, and JavaScript that rarely change, an aggressive caching policy (e.g., one year) combined with the immutable directive is non-negotiable. This ensures that for repeat visits, these files are loaded instantly from the disk, not the network.

2. Compression

Sending uncompressed text based assets (HTML, CSS, JS) over the network is a massive performance bottleneck. This header confirms that your server has compressed the file using an efficient algorithm like Brotli (br) or Gzip (gzip). Proper compression can reduce file sizes by over 70%, drastically cutting down download times, especially on mobile networks.

3. Modern Protocols

The web has moved beyond the limitations of HTTP/1.1. HTTP/2 introduced multiplexing, allowing multiple files to be downloaded over a single connection. HTTP/3, built on the QUIC protocol, goes even further by eliminating head-of-line blocking and speeding up connection establishment. We check not just that you're using a modern protocol, but that your server properly advertises HTTP/3 support via the alt-svc header—a crucial step for unlocking maximum performance.

4. Security Headers with Performance Benefits

Some security headers have a direct performance impact. The HSTS header, for example, tells the browser to only communicate with your site over secure HTTPS. For returning visitors, this eliminates an entire insecure-to-secure redirect cycle, saving a full network round trip and improving your Time to First Byte (TTFB).

This tool will analyze your URL's headers against these principles and more, providing a quantitative score and actionable, prioritized recommendations. Enter your URL above to begin.