Cookie Flag Checker

Cookie Flag Checker - Secure and HttpOnly Cookie Security Test

The Cookie Flag Checker helps you identify whether cookies set by a website use critical security attributes such as Secure, HttpOnly, and SameSite. Cookies often store authentication tokens, session IDs, and user preferences. If these cookies are misconfigured, attackers can exploit them via XSS, session hijacking, or cross-site request forgery (CSRF). This tool inspects response headers and highlights missing security flags so you can fix risks early.

What Is a Cookie Flag Checker?

A Cookie Flag Checker analyzes HTTP response headers and identifies cookies set by a website. It specifically checks whether cookies include security attributes like Secure and HttpOnly, which protect sensitive data from being intercepted or accessed by malicious scripts.

Understanding Secure and HttpOnly Flags

The Secure flag ensures cookies are sent only over HTTPS connections, preventing interception on insecure networks. The HttpOnly flag prevents JavaScript from accessing cookies, protecting them from XSS attacks. Together, these flags form the foundation of secure session handling.

Why Cookie Security Matters

Misconfigured cookies are a common cause of account hijacking and data breaches. Attackers often target session cookies because they grant authenticated access. Properly configured cookie flags significantly reduce the attack surface.

How This Tool Works

The Cookie Flag Checker sends a request to the target URL and reads the Set-Cookie headers returned by the server. Each cookie is analyzed to determine whether Secure, HttpOnly, and SameSite attributes are present.

Common Cookie Security Issues

• Session cookies missing Secure flag
• Authentication cookies accessible via JavaScript
• Cookies set without SameSite protection
• Legacy cookies remaining after HTTPS migration

SameSite Attribute Explained

SameSite controls whether cookies are sent with cross-site requests. SameSite=Lax provides basic CSRF protection, SameSite=Strict offers maximum isolation, and SameSite=None requires Secure=true. Modern browsers increasingly enforce SameSite rules.

Who Should Use This Tool?

This tool is valuable for website owners, developers, security auditors, penetration testers, and SEO professionals performing technical audits. It helps ensure compliance with modern browser security expectations.

SEO and Cookie Flags

While cookie flags are not a direct ranking factor, security issues affect user trust, browser warnings, and conversion rates. A secure site improves overall quality signals and reduces risk.

How to Fix Cookie Flag Issues

Most modern frameworks allow cookie flags to be set globally. Enable Secure and HttpOnly by default for session cookies, review third-party scripts, and test changes using this tool.

Best Practices

• Always use HTTPS
• Set Secure and HttpOnly on session cookies
• Use SameSite=Lax or Strict
• Audit cookies after CMS or plugin updates
• Remove unused or legacy cookies

Final Thoughts

Cookie security is a small configuration detail with a big impact. The Cookie Flag Checker gives you instant visibility into how your site handles cookies, helping you prevent common vulnerabilities before they are exploited.

FAQ

Related tools

Pro tip: pair this tool with Security Header Strength Checker and Exposed Admin Path Detector for a faster SEO workflow.

• Security Header Strength Checker — Grade security headers with detailed scoring, letter grades (A+ to F), and actionable recommendations.
• Exposed Admin Path Detector — Detect common admin URLs that may expose login panels or sensitive areas.
• Robots.txt Security Analyzer — Analyze robots.txt to detect exposed admin, login, and sensitive paths.
• Google Malware Checker — Check if site has malware.
• Security Headers Checker — Check if website implements essential security headers like CSP, HSTS, X-Frame-Options.