JWT Decoder & Generator

Decode, verify, and generate JSON Web Tokens in real time. 100% offline and client-side processing using the Web Crypto API.

How to Use This Tool
STEP 01
Decoding a JWT
Paste an encoded token into the left panel. The tool automatically decodes and formats its Header and Payload on the right panel.
STEP 02
Generating a JWT
Modify the JSON values in the Header or Payload fields on the right. The left panel updates instantly with the generated token.
STEP 03
Verifying Signatures
Enter a secret key into the signature box. The status box indicates whether the token's signature matches the secret.
Understanding JWT, Decoders & Generators

What is a JWT?

A JSON Web Token (RFC 7519) is a compact, URL-safe standard for transferring claims between two parties. It consists of three dot-separated parts: Header (algorithm & token type), Payload (claims/data), and Signature (verification hash).

What is a JWT Decoder?

A JWT Decoder unpacks the Base64URL-encoded Header and Payload sections into human-readable JSON format. Because Base64URL is an encoding scheme rather than encryption, anyone can decode and inspect the contents of an unencrypted JWT.

What is a JWT Generator?

A JWT Generator constructs a valid token by Base64URL-encoding custom Header and Payload JSON objects, then signing them using a cryptographic secret key (such as HMAC SHA-256) to ensure data integrity.