Cookie Parser: Decode Browser Cookies
Parse and inspect cookie strings — decode values, check attributes, and understand SameSite, HttpOnly, Secure.
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Cookie Parser: Decode Browser Cookies An HTTP cookie is a small piece of data sent by the server and stored by the browser. The raw header that controls this mechanism is deceptively complex — a single line that encodes the cookie value plus up to eight security-critical attributes. A cookie parser decodes that line so you can verify every attribute is set correctly. --- All the tools discussed here are available for free at theproductguy.in — client-side, no sign-up required. Part of the HTTP Debugging Tools Guide — a complete toolkit for diagnosing web requests. --- What is The Raw Set-Cookie Header? When a server wants to set a cookie, it includes a header in the HTTP response: The browser parses this header and stores the cookie. Every subsequent request to a matching domain/path…
Frequently Asked Questions
How do I parse a cookie string?
To parse a cookie string, split the string on semicolons — the first segment is the name=value pair, and each subsequent segment is an attribute. Online cookie parsers automate this: paste a raw Set-Cookie or Cookie header value and get each attribute annotated with its meaning and security impact.
What are cookie attributes?
Cookie attributes control scope and security: Path limits which URLs receive the cookie, Domain specifies which hosts can read it, Expires/Max-Age sets the lifetime, HttpOnly blocks JavaScript access, Secure restricts transmission to HTTPS, and SameSite controls cross-site sending behavior (Strict, Lax, or None).
What is an HttpOnly cookie?
An HttpOnly cookie has the HttpOnly flag set, which prevents client-side JavaScript from reading it via document.cookie. This is the primary defense against session token theft via XSS attacks — even if an attacker injects JavaScript, they cannot exfiltrate the token. All session cookies should be HttpOnly.
What is the SameSite cookie attribute?
SameSite controls whether a cookie is sent on cross-site requests. SameSite=Strict never sends the cookie cross-site. SameSite=Lax sends it on top-level navigations (clicking a link) but not on subresource loads (images, XHR). SameSite=None sends it on all cross-site requests but requires the Secure flag.
How do I inspect cookies in DevTools?
In Chrome or Firefox DevTools, open the Application tab (Chrome) or Storage tab (Firefox). Select Cookies in the left sidebar, then choose your domain. You can see every cookie with its name, value, domain, path, expiry, size, HttpOnly flag, Secure flag, and SameSite setting. You can also edit or delete cookies from this panel.
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