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Version: 0.1.0

Parsing & Decoding Cookie Values

Cookie Lens automatically detects and decodes structured cookie values, making it easy to inspect and edit complex data without manually decoding.

Supported Formats​

JSON​

Cookies containing JSON objects or arrays.

Example:

{"userId": "12345", "email": "[email protected]", "role": "admin"}

What Cookie Lens does:

  • Detects JSON automatically.
  • Pretty-prints for readability.
  • Lets you edit individual fields.
  • Re-encodes when saving.

Use cases:

  • User preference objects.
  • Session data.
  • Feature flag configurations.
  • Custom application data.

Base64​

Base64-encoded values.

Example:

eyJ1c2VySWQiOiAiMTIzNDUifQ==

Decodes to:

{"userId": "12345"}

What Cookie Lens does:

  • Detects Base64 encoding.
  • Automatically decodes.
  • Shows the decoded value.
  • Re-encodes after editing.

Use cases:

  • Compressed cookies.
  • Binary data encoding.
  • Legacy session formats.

JWT (JSON Web Tokens)​

JWT tokens with header, payload, and signature.

Example:

eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiaWF0IjoxNTE2MjM5MDIyfQ.SflKxwRJSMeKKF2QT4fwpMeJf36POk6yJV_adQssw5c

What Cookie Lens does:

  • Separates header, payload, and signature.
  • Decodes the payload (the actual data).
  • Shows readable claims (sub, name, iat, exp, etc.).
  • Displays expiration time.
  • Lets you inspect but not edit (signature becomes invalid if modified).

Common JWT claims:

  • sub — subject (user ID).
  • name — user name.
  • iat — issued at (timestamp).
  • exp — expiration (timestamp).
  • aud — audience.
  • iss — issuer.
  • Custom claims (your application-specific data).

Use cases:

  • Authentication tokens.
  • OAuth/OpenID Connect flows.
  • API authorization.
  • Secure session management.

URL-Encoded Data​

Data in URL parameter format.

Example:

param1=value1&param2=value2&nested=%7B%22key%22%3A%22value%22%7D

What Cookie Lens does:

  • Decodes URL encoding (%20, %7B, etc.).
  • Shows readable parameter names and values.
  • Lets you edit parameters.
  • Re-encodes with proper URL encoding.

Use cases:

  • Multi-parameter configuration.
  • Google Analytics cookies (__ga, __utm_*).
  • Tracking pixel parameters.
  • Legacy cookie formats.

URL-Encoded JSON​

JSON wrapped in URL encoding.

Example:

%7B%22userId%22%3A%2212345%22%2C%22role%22%3A%22admin%22%7D

Decodes to:

{"userId": "12345", "role": "admin"}

What Cookie Lens does:

  • Detects both layers (JSON + URL encoding).
  • Decodes both automatically.
  • Shows the JSON in readable format.
  • Edits the JSON normally.
  • Re-encodes both layers.

Use cases:

  • Encrypted or obfuscated data.
  • Legacy systems.
  • Cross-origin data passing.

Query Strings​

Semicolon or comma-separated key-value pairs.

Example:

sessionId=abc123; userId=456; theme=dark

or

lang=en,region=US,theme=dark

What Cookie Lens does:

  • Parses the key-value pairs.
  • Shows each key and value.
  • Lets you edit individual pairs.
  • Re-encodes with proper separators.

Use cases:

  • Multi-valued configuration cookies.
  • Legacy Apache/Tomcat cookie formats.
  • Custom application protocols.

Key-Value Pairs​

Simplified key-value format.

Example:

name:John,age:30,verified:true

What Cookie Lens does:

  • Parses the pairs.
  • Shows readable keys and values.
  • Lets you edit.
  • Re-encodes.

Use cases:

  • Custom application data.
  • Simple preference storage.
  • Legacy formats.

How to Edit Parsed Values​

Click on the cookie in Cookie Lens to open its details.

Step 2: Click Edit​

Click the Edit button to enter edit mode.

Step 3: Edit Decoded Value​

  • If it's JSON, click on individual fields to edit.
  • If it's JWT, note that you can view but not edit (signature would break).
  • If it's Base64 / URL-encoded, edit the decoded content directly.
  • If it's key-value pairs, edit the values inline.

Step 4: Save​

Click Save. Cookie Lens automatically:

  1. Re-encodes to the original format.
  2. Applies the change to the cookie.
  3. May reload the page.

Original cookie value:

{"userId": "12345", "theme": "light", "notifications": true}

You edit it to:

{"userId": "12345", "theme": "dark", "notifications": true}

Cookie Lens automatically:

  • Validates the JSON syntax.
  • Re-encodes any special characters.
  • Saves the modified value.
  • The page sees the updated theme preference.

Format Detection Priority​

Cookie Lens detects formats in this order:

  1. JWT — check for 3 parts separated by ..
  2. Base64 — check for base64 padding and valid decoded content.
  3. JSON — check for { or [ patterns.
  4. URL-encoded JSON — check for %7B (encoded {).
  5. URL-encoded — check for % patterns.
  6. Query string — check for = and & patterns.
  7. Key-value pairs — check for : separators.
  8. Plain text — if none match, display as-is.

Tips & Tricks​

Inspect Without Editing​

  • View decoded values without touching the cookie.
  • Useful for understanding what data is stored.
  • No risk of breaking the cookie.

Test with Different Data​

  • Edit a parsed value to test application behavior.
  • Change a role from user to admin.
  • Change a feature flag from true to false.
  • Use Mock instead of direct edit to preserve original.

Decode on the Fly​

  • Don't manually copy to a decoder tool.
  • Cookie Lens shows decoded values instantly.
  • Edit decoded values directly.

Validation​

  • JSON syntax is validated before save.
  • Invalid JSON shows an error.
  • Base64 validity is checked.
  • URL encoding is corrected if needed.

Complex Nesting​

For deeply nested JSON:

  • Click to expand or collapse sections.
  • Edit individual nested fields.
  • Changes cascade up to the root.

See Also​