HTTP headers
View all response headers sent by a web server, for every step in the redirect chain.
About this tool
Every time a browser fetches a page, the server first sends a number of HTTP headers. These tell the browser what the response contains, how long it may be cached, which cookies are set and which security rules apply.
The tool fetches the address and displays the headers exactly as the server sent them. If you're redirected to another address, the tool follows along and you can view the headers for each step.
Headers are useful to inspect when caching isn't behaving as expected, when a redirect is going wrong or when you want to confirm that security headers such as HSTS and CSP are actually being sent.
Frequently asked questions
What is cache-control?
This header tells the browser and any intermediate servers whether the response may be cached and for how long. max-age is specified in seconds.
Why isn't my new header showing up?
Check that the rule is in the correct file and that it applies to that specific address. A cache or CDN in front of the server may also serve an older response for a while.
What does location mean?
This header appears in redirect responses and specifies the address the browser should navigate to.