HTTP Header Analyzer: Inspect and Debug Response Headers

What Are HTTP Headers

HTTP headers are metadata fields sent between clients and servers with every request and response. They control caching behavior, specify content types, manage authentication, enforce security policies, and enable features like compression and CORS. Understanding headers is fundamental to debugging web applications, optimizing performance, and securing APIs.

While browser DevTools show headers for individual requests, an HTTP header analyzer provides a focused view that highlights security issues, performance opportunities, and configuration problems. It can flag missing security headers, warn about overly permissive CORS policies, and identify caching misconfigurations that hurt performance.

How to Analyze HTTP Headers

CheckTown's HTTP Header Analyzer inspects response headers and provides actionable insights for security and performance.

• Enter a URL to fetch its HTTP response headers and view them in a structured, categorized format
• Review security headers like Content-Security-Policy, Strict-Transport-Security, and X-Content-Type-Options
• Check caching headers (Cache-Control, ETag, Expires) to understand how the server manages content freshness
• Identify missing recommended headers with suggestions for what to add and why it matters

Essential Headers Every Developer Should Know

Certain HTTP headers appear in nearly every production web application and directly impact security, performance, and user experience.

• Content-Security-Policy restricts which resources a page can load, preventing cross-site scripting (XSS) and data injection attacks
• Strict-Transport-Security (HSTS) forces browsers to use HTTPS for all future requests, eliminating SSL stripping attacks
• Cache-Control governs how browsers and CDNs cache responses — correct settings dramatically improve load times and reduce server costs

Frequently Asked Questions

What is the difference between request headers and response headers?

Request headers are sent by the client (browser) to the server and include information like the accepted content types, authentication tokens, and browser identity. Response headers are sent by the server back to the client and include the content type, caching directives, security policies, and status information. The analyzer focuses on response headers because they reveal server configuration.

Why are security headers important?

Security headers like Content-Security-Policy, X-Frame-Options, and Strict-Transport-Security protect against common web attacks including cross-site scripting, clickjacking, and protocol downgrade attacks. Without them, even a well-coded application is vulnerable to client-side exploitation. Security scanners and compliance audits check for these headers.

Can I analyze headers for any website?

The analyzer can inspect headers for any publicly accessible URL. Some sites may block automated requests or return different headers based on the client, but for most websites you will see the same response headers that browsers receive. For private or localhost URLs, you can paste the raw header text directly.