HTTP Header Analyzer — Free Online Tool Analyze HTTP headers locally for caching, CORS, cookies, CSP, HSTS, content types, and common security configuration gaps.
Use this free online HTTP Header Analyzer directly in your browser. No signup required, no data leaves your device. Part of Utilier — a collection of 133+ developer utilities.
What is HTTP Header Analyzer? HTTP headers are metadata attached to a request or response. They describe content formats, caching behavior, cross-origin access, cookies, redirects, authentication, and browser security policies.
Security review: Checks common response protections such as Content-Security-Policy, HSTS, X-Content-Type-Options, and cookie attributes.Caching and CORS: Explains Cache-Control and Access-Control-Allow-Origin values that affect performance and browser access.Local analysis: Parses pasted header text only; it does not contact the target server.Why use header analyzer? A raw header block is compact but hard to evaluate quickly. Focused warnings make it easier to spot an absent cache policy, an overly broad CORS origin, or cookies that lack the attributes appropriate for authenticated sessions.
When to use header analyzer Use it with headers copied from browser DevTools, curl, a proxy, or server logs. Each recommendation needs application context: a public asset and an authenticated API response have different correct policies.
How to use header analyzer Paste headers: Include an optional HTTP status line followed by Header: value lines.Read the findings: Review caching, CORS, cookies, and security-policy messages.Verify intent: Apply changes only after confirming the resource and deployment requirements.Examples Cookie review Set-Cookie: session=abc; Path=/Warns when Secure, HttpOnly, or SameSite are absent.CORS review Access-Control-Allow-Origin: *Flags the wildcard as a policy decision requiring review.Frequently asked questions Does a missing header always mean a vulnerability? No. The correct policy depends on the resource, but a missing header is a useful review prompt.
Does this send a request? No. It analyzes only the text you paste.
Can it replace a security review? No. It identifies common configuration signals; production policies need application-specific review.
Privacy and availability Runs entirely in your browser — zero server processing No signup or account required Works offline once loaded Fast, lightweight, no external dependencies Available as a browser extension for Chrome and Firefox Tags HTTP Networking Security API Related tools CSP Generator & Evaluator — Build a Content-Security-Policy from directives and lint any pasted CSP for common weaknesses.HTTP Status Codes — Searchable reference of HTTP response status codes with their names and meanings.API Tester — Lightweight REST, GraphQL & WebSocket client with auth, body types, query params, and request history.cURL Converter — Convert a curl command to fetch, Axios, React, Python, Go, PHP, Java or Rust — and fetch back to curl.All developer tools JSON Beautifier & Validator — Format, minify and validate JSON. Reports the exact error location.HTML Beautifier & Minifier — Indent or minify HTML. 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