Online JWT Decoder

Our free online JWT Decoder allows you to decode and parse JSON Web Tokens (JWT) instantly without any verification. Simply paste your JWT token and view the header, payload, and signature components in a readable format.

Features:

• Instant Decoding: Decode JWT tokens instantly without any server-side processing - all done in your browser.
• Header Analysis: View the algorithm (alg) and token type (typ) from the JWT header.
• Payload Inspection: Examine all claims including standard claims (iss, sub, aud, exp, iat) and custom claims.
• Expiration Check: Automatically detect and display token expiration status.
• Secure & Private: Your tokens never leave your browser - no data is sent to any server.

1. What is a JWT Token?

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. JWTs are commonly used for authentication and information exchange in web applications.

2. JWT Structure

A JWT consists of three parts separated by dots (.): Header, Payload, and Signature. The header typically contains the token type and signing algorithm. The payload contains the claims (user data). The signature ensures the token hasn't been tampered with.

3. Common JWT Claims

iss (Issuer): Who issued the token
sub (Subject): The subject of the token (usually user ID)
aud (Audience): Intended recipient of the token
exp (Expiration): Token expiration timestamp
iat (Issued At): When the token was issued
nbf (Not Before): Token not valid before this time

4. Why Decode JWT?

Decoding JWTs is essential for debugging authentication issues, verifying token contents, understanding API responses, and ensuring your application correctly handles user sessions and permissions.

5. Security Notice

This tool only decodes the JWT without verifying the signature. Never use decoded data from untrusted sources without proper verification. Always validate tokens on your server before trusting their contents.