# HTTP Security Headers Checker

> Free paste-mode HTTP security headers checker for localhost, staging, and private environments. Analyze headers without fetching a public URL.

- **Category:** Developer
- **URL:** https://www.teafun.cyou/tools/http-headers-checker/
- **Privacy:** Runs entirely in your browser — no uploads, no account, no tracking.
- **Also known as:** http headers, security headers, csp, cors, response headers, check headers, website headers
- **Related tools:** [Log Formatter](https://www.teafun.cyou/tools/log-formatter/), [JWT Decoder](https://www.teafun.cyou/tools/jwt-decoder/), [JSON Formatter & Validator](https://www.teafun.cyou/tools/json-formatter/)
- **Tags:** Data, Security

## About

Paste raw response headers or curl -I output to review common security headers locally, including CSP, HSTS, and COOP.

## How to Use the HTTP Security Headers Checker

Run `curl -sI https://your.endpoint/` or copy from DevTools -> Network -> Headers -> Response. Paste the full block including the status line (`HTTP/2 200`). The checker tolerates redirects (`301`/`302`/`307`/`308`) and scores the final response. Each header is evaluated against the OWASP recommended value: Pass (matches recommendation), Warn (present but weak — e.g., HSTS `max-age=300` is too short to be effective), Fail (missing or actively unsafe — e.g., `Access-Control-Allow-Origin: *` with credentialed endpoints). The report links each finding to the relevant MDN docs and the OWASP cheat-sheet. A common trap: setting both `X-Frame-Options: DENY` and `Content-Security-Policy: frame-ancestors 'none'` is redundant but not wrong — `frame-ancestors` wins on modern browsers, X-Frame-Options remains for legacy. CSP `'unsafe-inline'` in `script-src` defeats the policy for XSS protection; flagged as Fail even if the rest of CSP is solid.

## Why HTTP Security Headers Matter

Missing security headers are the most common finding in penetration tests because they are invisible: a site can serve the right HTML and still fail an audit because the response headers are wrong. PCI DSS 4.0 (March 2025), SOC 2 Trust Service Criteria, and the ISO 27001:2022 Annex A 8.26 all flag missing CSP / HSTS / X-Frame-Options as control gaps. The cost of fixing is one line in your reverse proxy (`add_header Strict-Transport-Security "max-age=31536000; includeSubDomains; preload" always;` in nginx, one block in `vercel.json` headers, three lines in Cloudflare Workers) — but undiscovered until an auditor or a competitor's security write-up surfaces it. CI-integrated header checking catches regressions: a deploy that flips your CSP from `default-src 'self'` to `default-src *` because someone debugging copy-pasted the wrong rule. Running the headers through this checker before merging the deploy PR catches the diff.

_SEO title: HTTP Security Headers Checker – Paste Mode | TeaFun_

## FAQ

### Can I paste localhost or staging headers?

Yes. This tool is built for paste mode, so you can review headers from localhost, internal staging, or any private environment without exposing the URL.

### Why not fetch the URL directly?

Fetching a URL would fail for many private environments and could leak internal endpoints. Paste mode keeps the workflow private and works anywhere curl or browser devtools can copy headers.

### Does a high score guarantee security?

No. The checker highlights common response headers and common misconfigurations, but it is not a full application security audit.