What response headers tell you
Every web page arrives with a set of headers that describe the response before the content itself: its type, how long it can be cached, which server sent it and more.
Reading these headers helps you debug slow pages, confirm security settings and understand how a server treats a particular URL.
How to view headers
- Enter the URL you want to inspect.
- Press get headers and wait a moment.
- Review the status line and response time.
- Scan the header table for the details you need.
- Compare headers across pages to spot differences.
Headers worth checking
- Content-Type says what kind of file the server sent.
- Cache-Control shows how long browsers may reuse the copy.
- Server names the technology behind the site.
- Strict-Transport-Security enforces secure connections.
- Content-Security-Policy limits what scripts can run.
When to use this checker
Use it after enabling a security plugin, when a page will not cache correctly, or when a download serves the wrong file type. The headers often reveal the cause in a single glance.
Frequently Asked Questions
It is a line of metadata sent by the server with each response, describing details like the content type and caching rules.
The Content-Length header shows the body size in bytes. It may be missing on some servers.
It tells the browser how to handle the response, such as text/html for a page or image/jpeg for a picture.
It tells browsers and proxies how long to keep a cached copy, which affects how fast returning visitors load your pages.
Yes. The checker shows the headers of the first response, including the redirect status and the new location.
No. The request is made once and the result is shown immediately in your browser.
It works for most public pages. Some sites block automated requests and will not respond to the checker.