JWT Inspector & Decoder

Decode and inspect JSON Web Tokens instantly in your browser. View headers, payloads, and signatures with our secure, client-side JWT decoder.

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Decode Your JWT Token

Paste your JWT token below to instantly decode and inspect its header, payload, and signature. All processing happens in your browser - your tokens never leave your device.

Paste your JWT token below

All tokens are decoded locally in your browser and never sent to our servers.

Understanding JWT Tokens

A comprehensive guide to JSON Web Token structure and components

Header

Contains metadata about the token, including the signing algorithm (e.g., HS256, RS256) and token type (JWT).Example: {"alg": "HS256", "typ": "JWT"}

Payload

Contains the claims - statements about the user and additional data. Includes standard claims like exp, iat, sub, and custom claims.Claims: sub (subject), exp (expiration), iat (issued at)

Signature

Used to verify the token hasn't been tampered with. Created by encoding the header and payload with a secret key.Ensures token integrity and authenticity

Common Use Cases

Debugging Authentication

Quickly inspect JWT tokens to verify claims, expiration times, and user information when troubleshooting auth issues.

API Development

Validate that your API is issuing tokens with the correct structure, claims, and expiration settings.

Learning & Education

Understand how JWTs work by decoding real tokens and seeing the three-part structure in action.

Security Audits

Review token claims and expiration policies to ensure your authentication implementation follows security best practices.

Frequently Asked Questions

Common questions about JWT tokens and decoding

What is a JWT (JSON Web Token)?

A JWT (JSON Web Token) is a compact, URL-safe token format used for securely transmitting information between parties. It consists of three parts: header, payload, and signature, encoded in Base64.

Is it safe to decode JWTs in my browser?

Yes, our JWT decoder runs entirely in your browser with no data sent to any server. All decoding happens client-side using JavaScript, ensuring your tokens remain private and secure.

How do I validate a JWT signature?

JWT signatures are validated using the secret key or public key (for asymmetric algorithms). Our tool decodes the token to show its structure, but signature validation requires the secret/public key on your server.

What are the three parts of a JWT?

A JWT consists of three Base64-encoded parts separated by dots: 1) Header (algorithm and token type), 2) Payload (claims and data), and 3) Signature (verification hash).