HTTP · APIs
HTTP Headers Inspector online
Enter a URL to review its HTTP response, redirects, caching, compression, cookies and security headers.
Inspect URL
HTTP guide
What are HTTP headers?
HTTP headers contain metadata about requests and responses between a client and a server. They describe content, caching, security and other technical details.
Why inspect them?
They are useful for debugging, technical SEO, caching, security, APIs, redirects and web performance.
Important HTTP headers
Content-Type describes the format; Cache-Control controls caching; Location indicates redirects; Content-Encoding shows compression; CSP and HSTS help strengthen security; Set-Cookie defines cookies.
HTTP status codes
2xx codes indicate success, 3xx redirects, 4xx client errors and 5xx server errors.
Frequently asked questions
Questions about HTTP headers
What is an HTTP header?
It is metadata accompanying an HTTP request or response that describes technical communication details.
How can I check a URL’s headers?
Enter a public URL and select Inspect headers.
What does a 301 mean?
It is a permanent redirect indicating that a resource moved to another URL.
How can I tell if a website uses caching?
Review Cache-Control, Expires, Age, ETag and Last-Modified in the result.
How can I check for gzip or Brotli?
Check Content-Encoding; it may indicate gzip, br or deflate.
Which security headers should a website have?
It depends on the site, but HSTS, CSP, X-Content-Type-Options and Referrer-Policy are common.