HTTP Header Security Checker
Analyze HTTP response headers for missing or misconfigured security policies. Verify CSP, HSTS, X-Content-Type-Options, Referrer, and Server version leakage. Generate ready-to-deploy fix snippets for your server.
Paste your raw HTTP response headers block, or a JSON payload containing headers, to analyze security directives and discover fix suggestions.
Why Use Our HTTP Header Security Checker?
Intelligent Scoring System
Grades security posture from A+ to F using an OWASP-aligned points system. Easily spot which missing headers hurt your security posture the most.
Deep Directive Inspection
Inspects directive strings in CSP and HSTS for unsafe flags like unsafe-inline, wildcard sources, or low max-age settings beyond simple existence.
Multi-Server Fix Snippets
Generates custom copy-paste header configurations for Nginx, Apache, Cloudflare, Next.js, Vercel, and Caddy to deploy security fixes instantly.
100% Client-Side Privacy
No data is sent to external servers. All header parsing, security grading, and code generation run entirely locally in your browser for absolute confidentiality.
Common Use Cases for HTTP Header Security Checker
Hardening Web Applications
Audit production site response headers to ensure optimal security settings. Identify missing policies before deployment to protect user sessions from interception.
Auditing APIs
Analyze gateway headers for microservices to verify CORS, authentication, and cookie properties. Prevent data leakage through API responses that external partners consume.
Verifying Deployments
Inspect headers after cloud releases on Vercel, Netlify, or AWS. Confirm that security policies are applied correctly in your load balancers and reverse proxies.
Security Education
Learn the standard set of security headers recommended by OWASP. Get detailed recommendations on what directives are secure and how they protect visitors.
Compliance Auditing
Perform checks for industry standard audits like PCI-DSS, SOC2, or HIPAA. Verify that transport hardening and frame restriction policies are in place.
Fixing Configuration Errors
Debug misconfigured CSP directives, HSTS timeouts, or weak SameSite cookie attributes. Generate ready-to-use fixes for your web server configuration.
About HTTP Header Security Checker
Understanding HTTP Security Headers
HTTP security headers are response metadata directives sent by a web server to tell the browser how to behave when rendering a site. These headers form the first and most cost-effective line of defense against client-side attacks. By setting rules on scripting, dynamic framing, and connection channels, security headers help block attacks before they reach critical code paths.
Content Security Policy (CSP) & Directives
Content-Security-Policy (CSP) is one of the most powerful headers. It defines which origins and types of assets (scripts, stylesheets, images, fonts, connections) the browser is allowed to load. A strict policy restricts inline scripts and eval, preventing attackers from injecting arbitrary code. Modern CSP policies can also restrict framing behaviors using the frame-ancestors directive.
HSTS & Transport Security Safeguards
HTTP Strict Transport Security (HSTS) tells browsers to communicate with a domain exclusively over secure HTTPS channels. HSTS caches this preference locally in the browser for a specified max-age duration. By pairing HSTS with the includeSubDomains directive and submitting your site to the preload list, you guarantee that users will never connect over insecure HTTP, mitigating MITM risks.
Mitigating Information Leakage
Many web servers automatically include headers like Server, X-Powered-By, or X-AspNet-Version in their responses. These banners disclose the names and exact versions of web servers, runtime engines, or framework technologies. Stripping these banners hinders attackers from easily fingerprinting your stack and mapping out vulnerabilities for automated scanning.
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Frequently Asked Questions About HTTP Header Security Checker
An HTTP Header Security Checker analyzes the HTTP response headers returned by your web server. It audits them for missing, deprecated, or misconfigured headers (like CSP, HSTS, and X-Content-Type-Options) to evaluate your overall security posture and assign a letter grade.
The checker audits critical security headers: Content-Security-Policy (CSP), Strict-Transport-Security (HSTS), X-Content-Type-Options, X-Frame-Options, Referrer-Policy, Permissions-Policy, X-XSS-Protection, and server version leakage banners (Server, X-Powered-By, X-AspNet-Version).
It starts with a baseline score of 100. Deductions are made based on severity: -25 for missing Content-Security-Policy, -20 for missing Strict-Transport-Security, and -10 for other missing headers or insecure configurations (e.g. unsafe-inline scripts in CSP). A score of 95+ gets an A+ grade, while <60 gets an F.
A CSP is marked as weak or insecure if it permits unsafe-inline scripts, unsafe-eval execution, or allows wildcards (*) and HTTP origins. These values undermine standard clickjacking and cross-site scripting protections by letting browsers execute scripts from unauthorized sources.
Built-in browser XSS filters in older versions of Chrome, Safari, and IE had vulnerabilities that could be exploited to bypass security or execute scripting attacks. Modern security best practice recommends disabling these legacy filters by setting the header to 0 and using a strong CSP instead.
Yes. Since the parser runs entirely client-side on your browser, you can copy response headers from your local terminal curl outputs, browser developer tools network tab, or API clients and paste them directly into the analyzer to verify your development environment configuration.
The tool provides custom config snippets for popular environments like Nginx, Apache, Cloudflare, Next.js, Vercel, and Caddy. Choose your server platform tab, copy the generated configuration code, and add it to your server configuration file or deployment rules.
No. The HTTP Header Security Checker runs entirely in your web browser. All parsing, evaluation, and code snippet generation happen locally. None of your headers or configuration information is transmitted or stored on our servers, ensuring complete privacy.
Yes. The tool is 100% free with no registration, email subscription, or configuration limits. You can perform as many response header security audits as you need with instant, secure browser-based results.