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Cookie Security Checker

Inspect Secure, HttpOnly, SameSite, Domain, Path and expiration settings across one or more Set-Cookie headers.

Paste one or more Set-Cookie values, or enter a public website URL to inspect cookies returned by the server.
0
Not analyzed

Run the checker to evaluate cookie security.

Cookies Found 0 Set-Cookie headers
Secure 0 HTTPS-only cookies
HttpOnly 0 blocked from JavaScript
SameSite Set 0 cross-site policy defined
High-Risk Cookies 0 important weaknesses
Strong Cookies 0 recommended protections
Persistent 0 Expires or Max-Age set
Broad Domain 0 shared across subdomains

๐Ÿ”Ž Security Findings

๐Ÿ’ก Recommended Improvements

๐Ÿงพ Normalized Cookie Headers

๐ŸŒ Source Information

HOW IT WORKS

Manual Analysis in Your Browser, Live Checks From Our Server

Pasting Set-Cookie header values and analyzing them for Secure, HttpOnly, SameSite, prefix and expiration rules happens entirely in your browser - nothing is sent anywhere. Checking a live website is different: browsers deliberately hide the Set-Cookie response header from cross-origin JavaScript, so our .NET backend fetches the page instead and reads the raw Set-Cookie headers directly off the HTTP response (never a comma-merged approximation). The same SSRF protections used across our security tools apply here too - private, loopback, link-local and cloud-metadata addresses are always rejected, and every redirect hop is re-validated before being followed. The backend never stores or logs the cookie values it reads, and only response headers are fetched - the page body is never downloaded.

COMMON QUESTIONS

Cookie Security Checker FAQ

Why does SameSite=None without Secure matter?

Modern browsers reject cookies marked SameSite=None unless they also have the Secure flag, so this combination usually means the cookie will silently fail to be set at all - a functional bug as much as a security one.

What do the __Host- and __Secure- prefixes do?

These are browser-enforced naming conventions: a __Host- cookie must have Secure, no Domain attribute, and Path=/, while a __Secure- cookie must have Secure set. Browsers reject a Set-Cookie header that uses the prefix without meeting its rules.

Can I check an internal or private site's cookies?

No. Hostnames that resolve to localhost, private IP ranges, link-local addresses or cloud metadata endpoints are rejected before any request is made, and each redirect hop is re-validated the same way.

Does the backend store the cookies it reads?

No. Cookie values pass straight through the response and are never written to logs or storage - only the exception message is logged if a fetch fails, never response content.

Why does the tool disable normal cookie handling when fetching a site?

By default, .NET's HTTP client would quietly absorb Set-Cookie headers into its own cookie store instead of surfacing them - and would carry cookies between requests. This tool disables that entirely so each check is stateless and the raw headers are always returned.

Cookie Security Checker auditing each cookie for Secure, HttpOnly, SameSite and cookie prefix rules
Cookie Security Checker: Check Secure, HttpOnly, SameSite and cookie prefix rules.