Cookie Parser

Inspect Cookie / Set-Cookie attributes and consistency in your browser. No input is sent to a server. Use it for first-pass operational troubleshooting.

Status

Runs in your browser. No input is sent to a server. Use this as a first-pass diagnostic step.

How to use

Paste a Cookie header or cookie string and click “Parse”. A key=value list is displayed.

Notes (this tool)

  • Set-Cookie attributes are not parsed.

About this page

What does this tool do?

Paste a Cookie header (or cookie string) and it is split into key=value pairs.

It shows counts, duplicates, and value lengths to speed up inspection.

Typical use cases

  • Make Cookie values readable after copying from DevTools
  • Check for duplicate cookie names in a request
  • Get a quick feel for cookie size

Cookie is a request header carrying key=value pairs sent by the browser. Multiple cookies are separated by semicolons.

Attributes (Domain/Path/Expires, etc.) are only present in Set-Cookie.

What this tool does

  • Split Cookie header into key=value pairs
  • Handle multiple lines (multiple Cookie: lines)
  • Basic duplicate-name detection
  • Rough value length per cookie

Notes

  • Set-Cookie attributes are not parsed (use Cookie Inspect)
  • URL decoding is not performed

Debugging workflow (recommended)

  • Paste Cookie or Set-Cookie values
  • Review attributes such as Secure, HttpOnly, and SameSite
  • Check Domain and Path conflicts with related tools

Operational notes

  • Behavior can vary with browser implementation differences and default changes.
  • Duplicate cookie names and Path or Domain differences often cause operational issues.

Referenced specs

  • RFC 6265 (HTTP Cookies)
  • MDN: Cookie header

FAQ

Can I paste multiple Cookie: lines?

Yes. Each line is parsed and aggregated.

Can this parse Set-Cookie?

No. Use Cookie Inspect for Set-Cookie.

References

  1. RFC 6265 (HTTP Cookies)
  2. MDN: Cookie

These links are generated from site_map rules in recommended diagnostic order.

  1. How to Diagnose Set-Cookie Not Persisting — Isolate cookie persistence failures by checking Domain/Path/Secure/SameSite in order
  2. How to Diagnose Same-Name Cookie Collisions — Resolve unstable behavior by tracing same-name cookie path/domain variants, overwrite order, and send collisions
  3. Cookie Size Checker — Estimate Cookie header size and check limit risks
  4. HTTP Header Parser — Parse raw headers into structured lists
  5. Cookie Domain/Path Matcher — Evaluate cookie send conditions by Domain/Path/Secure
  6. SameSite Cookie Simulator — Simulate cookie send behavior from SameSite and request context

Example

Cookie: sid=abc; theme=dark; lang=en