JWT Decoder

Paste your JSON Web Token below to decode its header and payload.

Encoded JWT:

Understanding JSON Web Tokens (JWTs)

JSON Web Tokens (JWTs) are an open, industry standard (RFC 7519) method for representing claims securely between two parties. This decoder helps you inspect and understand the contents of JWT tokens without verification.

Token Structure

Header: Algorithm and token type metadata
Payload: Claims and user information
Signature: Cryptographic verification data
Format: header.payload.signature
Encoding: Each part is Base64URL encoded
Separation: Parts separated by dots (.)

Common Header Fields

alg - Signing algorithm (e.g., HS256, RS256)
typ - Token type (usually "JWT")
kid - Key ID for key rotation
cty - Content type (for nested JWTs)
crit - Critical header parameters

📋 Claims Reference

Registered Claims

iss Issuer

Identifies the principal that issued the token

sub Subject

Identifies the principal that is the subject of the JWT

aud Audience

Recipients that the JWT is intended for

exp Expiration

Time after which the JWT expires (Unix timestamp)

Additional Claims

nbf Not Before

Time before which the JWT must not be accepted

iat Issued At

Time at which the JWT was issued (Unix timestamp)

jti JWT ID

Unique identifier for the JWT

custom Private Claims

Application-specific claims (e.g., roles, permissions)

Security Analysis

🔍 What to Check

Algorithm: Verify expected signing algorithm
Expiration: Check if token is still valid
Issuer: Confirm token source is trusted
Audience: Ensure token is intended for your app
Claims: Validate all security-relevant claims
Signature: Always verify in production!

⚠️ Security Warnings

No Verification: This tool only decodes, doesn't verify
Sensitive Data: JWTs are not encrypted by default
Algorithm None: Beware of unsigned tokens
Key Confusion: Validate algorithm matches expected
Replay Attacks: Implement proper token tracking
Storage: Use secure storage mechanisms

🕒 Timestamp Decoder

Unix timestamps in JWTs can be converted to human-readable dates:

Current Time

1750048332

6/16/2025, 4:32:12 AM

Example: 1516239022

1/18/2018, 1:30:22 AM

1 Hour from Now

1750051932

6/16/2025, 5:32:12 AM

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