Analyze HTTP Response Headers Online
Check security, caching, CORS and server headers in one place
Paste raw HTTP headers above, or click Sample to try an example
Use this HTTP Header Analyzer to inspect raw response headers and understand what they mean. It helps developers, DevOps engineers, QA teams, security reviewers and website owners review headers copied from browser DevTools, curl, Postman, API clients, proxies or server logs. The tool is useful when debugging CORS errors, cache behavior, redirects, content types, security scanner warnings or unexpected browser behavior. Paste a header block to identify important security, caching, content and connection headers, then review what may need attention before changing server or CDN configuration.
How to Analyze HTTP Response Headers
Copy your headers from DevTools or curl, paste them in, and get an instant security and caching report.
Get your raw headers
In Chrome: open DevTools (F12), go to the Network tab, reload your page, click the main document request, then click the Headers tab and scroll to Response Headers. Select all the header text and copy it. Alternatively, run curl -I https://yourdomain.com in your terminal to fetch just the headers. Paste the raw output directly into the textarea.
Read the annotated header table
Each parsed header appears in a table row with its name, value, a color-coded category badge (Security, Caching, Content, Connection, or CORS), and a plain-English explanation of what it controls and why it matters. Headers flagged as security-relevant display a shield icon.
Fix missing security headers
The Missing Security Headers panel lists any of the five critical security headers absent from your response: Strict-Transport-Security, Content-Security-Policy, X-Frame-Options, X-Content-Type-Options, and Referrer-Policy. Each missing header links to documentation explaining how to add it to your web server, CDN (Cloudflare, Fastly), or application framework.
Features
Parses raw HTTP response headers into readable rows
Explains common security, caching, content and CORS headers
Detects missing security headers that may deserve review
Highlights caching directives such as no-store, no-cache and max-age
Identifies CORS headers used for cross-origin browser requests
Helps debug browser, API, CDN and server response behavior
Supports headers copied from DevTools, curl, Postman or logs
Separates useful signals from noisy server and proxy headers
Guides review of HSTS, CSP, X-Frame-Options and Referrer-Policy
Reduces guesswork when troubleshooting deployment and security issues
What This Tool Helps You Do
Analyze HTTP response headers so you can understand what a server, CDN, API gateway or application is telling the browser. Headers often explain problems that are not obvious in the page UI: blocked API calls, stale cache, missing security rules, wrong content type or unexpected redirects.
This tool turns a raw header block into a reviewable checklist for development, QA, security and deployment debugging.
Why Header Review Matters
HTTP headers control behavior before users ever see the page. Cache-Control can decide whether the browser reuses an old response. CORS headers can allow or block frontend API calls. Security headers such as HSTS, CSP, X-Frame-Options and Referrer-Policy can reduce common browser-side risks when configured correctly.
The key insight: a header can be present and still be wrong. For example, a CSP that is too strict may break scripts, while a CORS rule that is too broad may expose an API more than intended.
Practical Ways to Use This Tool
- Inspect response headers copied from browser DevTools or curl
- Check whether expected security headers are present
- Review CORS values when frontend requests fail
- Understand Cache-Control behavior during deployment issues
- Compare staging and production headers with a text diff checker
- Decode related bearer tokens with a JWT decoder when debugging auth headers
- Format API response samples with a JSON formatter while reviewing header and body behavior
- Find noisy or unnecessary disclosure headers such as X-Powered-By
What to Check Before Making Changes
Do not add headers blindly. Security headers can change how browsers load scripts, frames, fonts and external assets. Caching headers can make fixes appear delayed. CORS changes can affect authentication, cookies and browser-only request behavior.
Test changes in staging, verify the exact route being served and confirm whether headers come from the app, reverse proxy, CDN or hosting layer.
Expert Tips
Use curl -I for a fast first look, then confirm in browser DevTools because browsers may show redirects, preflight requests and final response headers separately. Review the main HTML document, API responses and static assets independently; they often need different header rules.
For production debugging, save the before-and-after header blocks so you can compare the exact change instead of relying on memory.
Common Mistakes to Avoid
- Assuming all routes send the same headers
- Adding a strict CSP without testing third-party scripts and fonts
- Using wildcard CORS with credentials-sensitive endpoints
- Setting long cache lifetimes on HTML pages that change often
- Forgetting that CDN headers may override application headers
- Checking only the first redirect instead of the final response
- Removing disclosure headers but ignoring more important missing protections
- Treating a scanner warning as context-free proof of a vulnerability
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Frequently Asked Questions
What does an HTTP header analyzer do?
It parses raw HTTP response headers and explains what each important header controls. This helps you understand security rules, caching behavior, content type, CORS settings and server response details.
How do I get response headers from a website?
Open browser DevTools, go to the Network tab, reload the page and select the main request. You can copy response headers from the Headers panel, or use a terminal command such as curl -I for a quick header-only check.
Can this tool detect missing security headers?
Yes. It can help flag commonly expected headers such as Strict-Transport-Security, Content-Security-Policy, X-Frame-Options, X-Content-Type-Options and Referrer-Policy. Missing headers do not always mean a site is broken, but they should be reviewed.
Does this tool fix HTTP headers automatically?
No. It analyzes and explains headers, but changes must be made in your server, CDN, hosting platform or application framework. Always test header changes in staging before applying them to production.
Is Content-Security-Policy always required?
A Content-Security-Policy can reduce certain script injection risks, but it must be configured carefully. A bad CSP can break scripts, images, fonts or third-party integrations if allowed sources are incomplete.
Why are CORS headers important?
CORS headers tell browsers which origins can access a resource from another domain. They are commonly involved in frontend API errors, especially when Access-Control-Allow-Origin or credentials settings do not match the request.
When should I review Cache-Control headers?
Review Cache-Control when pages show stale content, static assets do not update, private pages are cached, or CDN behavior does not match expectations. Cache rules can improve performance but can also hide deployment changes.
What is the risk of exposing X-Powered-By?
X-Powered-By can reveal framework or server technology. It is not a vulnerability by itself, but reducing unnecessary technology disclosure is a common hardening step.
Can I analyze API response headers?
Yes. API headers are useful for checking CORS, content type, rate limits, cache behavior, authentication challenges and gateway behavior. Copy the response headers from your API client or browser network panel.
What should I check before changing headers?
Check the purpose of each header, test changes in a safe environment and verify the page still loads correctly. Security and caching headers can affect login flows, embedded content, APIs, assets and third-party scripts.
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