What are HTTP headers?

HTTP headers are metadata sent along with HTTP requests or responses. They contain information about content type, caching, security and other parameters.

What does status code 200 mean?

HTTP 200 OK — the request was successful. The server returned the requested resource.

What does status code 301 mean?

HTTP 301 Moved Permanently — permanent redirect. The resource has moved to a new URL.

What does status code 404 mean?

HTTP 404 Not Found — the requested resource was not found on the server.

What does status code 500 mean?

HTTP 500 Internal Server Error — internal server error. The server could not fulfill the request.

Help — Enterno.io

Help HTTP Status Codes

How to Use

Standard Mode

Enter a URL in the URL field — the http:// protocol is optional and will be added automatically.
Click "Check" — the tool will make a request from the server and return the HTTP response headers.
Key headers (Content-Type, Server, Cache-Control, etc.) are shown immediately. Others are hidden — expand with the "More headers: N" button.
Redirect chains are displayed as separate blocks in order — each 301/302 step is visible.
Enable Show page HTML source to see the source code with syntax highlighting and a "Copy" button.

Advanced Mode

Method — GET (default), HEAD (headers only, no body), POST (with request body).
Referer — URL sent in the Referer header. Useful to test site behavior when coming from another domain.
Headers — additional HTTP headers, one per line: Accept-Language: en.
POST Body — request body for POST method (query string or JSON).
Do not follow redirects — the tool will stop at the first 3xx and show the Location header.
Timeout — maximum response wait time in seconds (1–30, default 15).
Max redirects — limit redirect chain depth (0–20).

User-Agent

Leave the field empty — the server default UA will be used.
Choose a preset from the dropdown: Chrome, Firefox, Safari, Edge, mobile browsers, Googlebot, Bingbot, curl.
Enter a custom UA manually — useful for checking mobile versions, responsiveness, and site behavior for bots.

WHOIS — Domain Information

After checking a URL, a WHOIS query is automatically made to the domain registry.
Brief view: registrar, creation date and expiration date — always visible.
Full view ("Details" button): registrar URL, update date, DNSSEC, domain status, name servers.
Raw WHOIS — complete response text from the registry WHOIS server.
Over 80 domain zones supported: .ru .com .net .org .io .de .uk .fr .co.uk .com.au and more.
Expiration date is color-coded: green — more than 90 days, yellow — up to 90 days, orange — up to 30 days, red — expired.
For some zones, registration data is hidden due to GDPR privacy policies — this is normal.

Header Color Coding

Content — Content-Type, Content-Length, Content-Encoding, Transfer-Encoding
Cache — Cache-Control, ETag, Expires, Last-Modified, Vary, Age
Location — redirect address
Cookie — Set-Cookie, Cookie
Security — Strict-Transport-Security, Content-Security-Policy, X-Frame-Options, X-Content-Type-Options, X-XSS-Protection
X-headers — non-standard headers starting with X-
Server — Server, X-Powered-By, Via