Secure JWT Decoder
Inspect and debug JSON Web Tokens instantly. 100% browser-side decoding—your sensitive security tokens never leave your device.
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What is a JWT?
JSON Web Token (JWT) is an open standard (RFC 7519) that defines a compact and self-contained way for securely transmitting information between parties as a JSON object. This information can be verified and trusted because it is digitally signed.
Header
Contains the type of token (JWT) and the signing algorithm used, such as HMAC SHA256 or RSA.
Payload
The claims (data) you want to transmit, such as user ID, role, and expiration timestamps.
Signature
Ensures that the token was not tampered with during transit. Only the issuer knows the secret key.
How to Decode a JWT
Security Notice
Unlike other JWT tools, iNNkie's decoder is entirely client-side. Your tokens are processed only in your browser's memory and are never transmitted over the network. This makes it safe for production security auditing.
Copy the raw encoded JWT string from your application or terminal.
Paste the string into the text area above. The tool will detect it automatically.
Inspect the Header and Payload JSON blocks. Use the timestamp helper to check expiration.
Understanding Standard JWT Claims
iss
Issuer
Identifies the principal that issued the JWT (e.g., Auth0, Firebase, or your own API).
sub
Subject
The unique identifier for the user or entity the token belongs to.
aud
Audience
Identifies the recipients that the JWT is intended for (e.g., your frontend URL).
iat
Issued At
The time at which the JWT was created, measured in Unix seconds.
Why Security Matters
Client-Side Isolation
When you paste a token into a server-side decoder, you are trusting that company with your session credentials. iNNkie removes that risk. The code that decodes your token runs entirely in your browser's memory and is destroyed when you close the tab.
No Logs, No Storage
Our platform does not log or store the tokens you decode. There is no database record of your security credentials, ensuring that even in the event of a platform breach, your private tokens remain private.
Secure Debugging Workflows
Auth Implementation
Verify that your authentication server is issuing tokens with the correct scopes, roles, and user identifiers. Inspect custom claims to ensure your frontend logic has the data it needs.
Expiration Debugging
Troubleshoot 'Session Expired' bugs by inspecting the 'exp' and 'iat' claims. Our tool converts Unix timestamps to local time so you can see exactly when a token will become invalid.
API Integration
Ensure your backend is receiving the expected 'aud' (Audience) and 'iss' (Issuer) values. Perfect for debugging multi-tenant applications and third-party integrations like Auth0 or Firebase.
DevOps & CI/CD
Quickly inspect tokens generated by service accounts or CLI tools during deployment. The 100% client-side nature makes it safe to use even with sensitive production credentials.
JWT Security FAQ
Is it safe to paste JWTs online?
iNNkie decodes your JWT entirely in your browser. Unlike other tools, we NEVER send your token to a server, making it the safest way to inspect security credentials.
Can I modify a JWT here?
iNNkie is currently a read-only inspector. This preserves the original signature structure and prevents accidental tampering while debugging.
What does 'exp' mean?
The 'exp' claim is the expiration time on or after which the JWT must not be accepted for processing. Our tool automatically converts this to a local date for you.