HTTP headers carry critical metadata exchanged between clients and servers that shapes caching, content negotiation, redirection, and security. Reading them helps you diagnose mixed-content warnings, verify compression, certify strict privacy directives, and reveal server software versions. Mastering header analysis accelerates performance tuning and compliance checks during web development and operations.

The HTTP Header Checker fetches each hop’s response through a lightweight browser script and presents names and values inside a sortable bordered table. A reactive interface mirrors every parameter change instantly, while the underlying HTTP client measures total time and retains results within your session. A one-click button also assembles an equivalent cURL command for sharing or terminal replication.

Use this tool when you need script-free insight into live headers for performance audits or security reviews; test only URLs you are authorised to inspect.

Technical Details:

Under the hood, the checker leverages the browser’s fetch capability through a concise wrapper to request only the header chain, avoiding payload downloads and conserving bandwidth. Results stay client-side, except the target URL sent to an open data API, so no cookies, tokens, or personal identifiers leave your device.

Dual Request Methods

Choose HEAD for rapid metadata retrieval or GET for full handshake validation, giving flexibility when dealing with servers that omit headers on head-only requests.

Instant cURL Generator

The interface assembles a reproducible cURL string matching every option, including timing, redirects, and custom headers, reducing copy-paste errors in documentation and command-line debugging.

Header Colorisation

Important directives, such as Cache-Control or Content-Security-Policy, appear in contrasting colours, letting you spot misconfigurations before they impact caching strategy or browser security posture.

JSON Export & Copy

Download the raw JSON response for version control or automated tests, or copy it instantly to clipboard for inclusion in bug reports and reproducibility records.

Redirect Trace View

By listing intermediate hops in sequence, the tool reveals CDN edges, HTTPS upgrades, and unexpected 301 loops, shortening root-cause analysis for SEO and security teams.

Step-by-Step Guide:

Follow these steps to inspect a URL’s headers and export results.

Enter the target address in the URL input box.
Click Advanced to reveal extra settings when needed.
Select the desired HTTP method and adjust any other options.
Press Check to run the request and populate results.
Switch between Table, Raw Header, or Raw JSON tabs for different views.
Use Copy to grab the cURL string or Download JSON for archival.

FAQ:

Find quick answers to frequent questions.

What counts as a hop?

Each distinct response in a redirect chain becomes one hop, allowing clear visibility into CDN, cache, or HTTPS upgrade layers.

Why do I see status code 0?

Status code 0 usually means the connection closed unexpectedly or a network error occurred before the server sent a valid response.

Is my data stored?

No. The tool keeps results in-memory and only transmits the target URL to the public API; nothing is logged or written server-side.

How accurate is timing?

The timer measures total client-side time including network latency. It may differ from server benchmarks taken closer to the origin.

How do I share results?

Copy the generated cURL command or download the JSON file, then paste it in chat, tickets, or automation scripts for reproducible testing.

Troubleshooting:

Resolve common issues quickly.

Empty response – The server may block HEAD requests; switch to GET and try again.
CORS error – A browser extension or strict policy is preventing fetch; disable extensions and retry.
Timeout exceeded – Increase the Timeout value in Advanced options for slow endpoints.
Copy button inactive – Clipboard permissions may be restricted; grant access or use the JSON download instead.
Invalid URL warning – Ensure the address includes the protocol (http or https) and contains no whitespace.

Advanced Tips:

Speed up diagnostics with expert tricks.

Use Accept-Encoding “identity” to see raw sizes without compression side-effects.
Toggle User-Agent presets to emulate bots and detect cloaked responses.
Add custom headers to test feature flags or API version negotiation.
Disable Follow redirects to inspect each hop individually and measure link rot.
Bookmark pre-filled parameter URLs to recreate tests instantly in future sessions.

Glossary:

Key terms at a glance.

Status Code: Numeric server response indicator, such as 200 or 404.
Redirect: Instruction guiding the client to fetch a different URL.
CORS: Browser policy controlling cross-origin resource sharing.
Cache-Control: Header specifying how responses may be stored and reused.
User-Agent: String identifying the client software initiating the request.

HTTP Header Checker

Introduction: