HTTP Header Checker

Display the HTTP response headers sent by a web server

Features

Retrieve HTTP headers

Retrieve the response headers of a specified URL on the server side and display them

Trace the redirect path

Follow 3xx redirects to the final destination and check the headers of each hop

Determine the status code

Color-code 2xx/3xx/4xx/5xx to grasp the response state at a glance

Copy headers

Copy the name and value of each item to the clipboard with one click

How to use

Enter a URL

Enter the URL of the page you want to check in the input field; the scheme can be omitted

Retrieve with the check button

Press the check button and the server retrieves and displays the headers

Check the headers and path

Check the status code and each header; redirects are shown in path order

Use cases

Checking cache settings

Verify cache behavior from Cache-Control and Expires

Inspecting security settings

Check whether defensive headers such as HSTS and CSP are present

Investigating redirects

Follow the destinations and number of hops to find loops or excessive redirects

Investigating server information

Infer the running environment and configuration from Server and X-Powered-By

Checking responses before release

Check status codes and configuration mistakes in advance just before release

Fundamentals

What are HTTP Response Headers

Response headers are supplementary information that servers return along with the page body, including cache handling, content type, server details, and redirect destinations.

Common Status Codes

200：200 is a status code indicating that the request was successful and content was returned normally.
301・302：301 and 302 are codes indicating that a page has moved to a different URL, with 301 meaning permanent and 302 meaning temporary redirection.
404・500：404 is a code indicating that a page does not exist, and 500 indicates a server internal error. These are the first values to check as starting points for investigating issues.