HTTP Header Checker

Introduction:

HTTP response headers are short lines of metadata that describe a response and guide how clients handle it. They reveal status, content type, caching hints, and the presence of redirects, so you can verify behavior and trace what a server actually returns.

Enter a full address, run the check, and read the result from top to bottom. You see a clear status summary, the final hop headers in a tidy table, and the full redirect chain in a raw and a structured view for deeper inspection.

A practical example is a homepage that returns a permanent move. You can confirm that the old address redirects to the new one, see cache directives, and note the timing so a slow first byte does not catch you off guard later.

Only the first non blank line of any pasted text is processed, so multi line lists are ignored with a short notice. For repeatable results, test with consistent addresses and keep parameters the same across runs.

The status label groups results by class for quick reading, then the table shows headers in alphabetical order for easy scanning. Use the structured output when you need the entire hop by hop story.

Technical Details:

Hypertext Transfer Protocol response headers describe the server’s reply at a specific moment. The tool records the apparent status code, the final hop header fields, and a simple elapsed time captured on the client.

Computation consists of resolving the supplied address through any redirects and extracting the last hop’s headers. The code also exposes the entire redirect chain in structured form for auditing and comparison between runs.

Results are interpreted by status class. Values in the 200 range indicate success, values in the 300 range indicate redirection, values in the 400 range indicate client errors, and values in the 500 range indicate server errors. Near the boundary, inspect the exact code before deciding next steps.

Comparability depends on using the same target, the same network conditions, and the same options. Keep in mind that the advanced selections for method, accepted encodings, and user agent affect only the companion command generator, while the live lookup always resolves and displays the chain.

1. Normalize the input to the first non blank line.
2. Request a header trace from a public relay with the address.
3. Receive an array of hops with status and fields.
4. Select the last hop as the effective response.
5. Render a status badge from the parsed code.
6. Sort fields alphabetically for the table.
7. Assemble a raw header block and a structured view.
8. Measure elapsed time on the client in seconds.

Units, precision, and rounding: elapsed time uses seconds with a dot as decimal separator and three fractional digits, computed with a client timer. No logarithms are used.

Networking and storage behavior: the page requests header traces from a public relay endpoint using the provided address, then renders the result locally. The app does not write to local storage or keep results after you leave the page.

Diagnostics and determinism: identical inputs produce identical displays for the same underlying server behavior. A status badge reflects the parsed digits even when the status line contains additional text.

Security considerations: avoid placing secrets in addresses. Be mindful that relay services can see the destination and returned headers. Limit tests on authenticated endpoints.

• Heads‑up Only the last hop populates the headers table; the chain appears in the structured view.
• Heads‑up Advanced options affect only the command helper, not the live lookup.
• Heads‑up Elapsed time includes network and render on the client and is approximate.
• Heads‑up Multi line input is reduced to the first non blank line with a notice.
• Heads‑up Sorting is case aware via locale rules and may group vendor fields together.
• Heads‑up The status parser extracts digits and ignores extra phrases.
• Heads‑up Extra headers and user agent selections are not sent in the live check.
• Heads‑up Timeouts limit the relay request rather than the destination directly.

• Empty address or whitespace only.
• Address with spaces or unescaped characters.
• Non HTTP scheme or invalid host.
• Endpoints that refuse the relay.
• Missing status line in a hop.
• Unusually large header values.
• Non printable characters in fields.
• Clipboard permissions blocked by policy.
• Network changes between retries.
• Relay unavailability or rate limits.
• Locale quirks in header sorting.
• Custom user agent left blank after selection.

Privacy & Compliance. Requests are issued from the browser to a public relay. No credentials are collected by this page, and no results are stored by the page itself.

How‑to · Check HTTP response headers

1. Paste a full address into the address field Required.
2. Select options in Advanced if you need a matching helper command.
3. Run the check and wait for the status summary.
4. Read the headers table for the final hop.
5. Open the structured view to inspect all hops.
6. Copy or download results for sharing.

You now have the status, headers, and timing in one snapshot you can share.

FAQ

Troubleshooting

• No output appears: confirm the address includes a scheme.
• Timeouts: increase the timeout value and retry.
• Empty headers: check the structured view for upstream hops.
• Unexpected status: repeat the run to rule out transient issues.
• Clipboard errors: use the download options instead.
• Sorting confusion: use the structured view to see original order.

Advanced Tips

• Tip Compare runs before and after deployments to spot header regressions.
• Tip Use a consistent address form with or without www to avoid mixed chains.
• Tip Inspect caching and vary query strings to see cache behaviors.
• Tip Watch for vary fields that change behavior across clients.
• Tip Note permanent moves during consolidation to keep links healthy.
• Tip Keep helper commands in source control when audits require provenance.

Glossary

HTTP

Application protocol for transferring hypertext documents.

Header

Name and value pair that modifies response handling.

Status code

Three digit number expressing the response outcome class.

Redirect

Instruction that points clients to a different location.

User agent

String that identifies the client making the request.

Accept‑Encoding

List of content codings the client can decode.

Latency

Elapsed time for a request and response cycle.

Structured view

Machine readable representation of hop by hop data.