Online JWT Token Decoder & Validator (JSON Web Token Tool)

This online JWT Decoder tool helps you quickly decode, inspect, and validate JSON Web Tokens (JWT) without sending data to any server. Paste a JWT token to view its decoded Header, Payload<, and Signature, understand token claims, and validate token structure using client-side JavaScript.

Contents

JSON Web Token Decoder

What is JWT?

JWT (JSON Web Token) is a compact, URL-safe token format used for securely transmitting information between parties. JWTs are commonly used for authentication, authorization, and secure API communication.

A JWT consists of three parts, separated by dots (.):

xxxxx.yyyyy.zzzzz
header.payload.signature

Header -
Contains metadata about the token, such as the signing algorithm (alg) and token type (typ).
Payload -
Holds claims like user identity, (user data, expiry, issuer, etc.) data. Payload data is encoded, not encrypted, and can be read by anyone who has the token.
Signature -
Used to verify that the token was not altered. It is created using the encoded header, payload, and a secret or private key.

JWT payload data is Base64URL-encoded, not encrypted. Anyone with the token can decode and view its contents.

Example token format:

eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9
.
eyJ1c2VySWQiOjEyMywiZXhwIjoxNzA2NjY2NjY2fQ
.
SflKxwRJSMeKKF2QT4fwpMeJf36POk6yJV_adQssw5c

When a server receives a JWT, it verifies the signature and checks claims like expiration (exp) before trusting the data.

This tool only decodes the token for inspection and does not perform signature validation.

JWT Decoder & Validator

Decode, inspect, and validate JSON Web Tokens (JWT) securely in your browser. The tool splits the token into Header, Payload, and Signature, converts Base64URL segments to readable JSON format, and checks expiration and claim integrity without sending data to any server.

How it works

Paste your JWT token
The token is decoded locally in your browser
Claims and expiration are validated
Results appear instantly below

Security & Privacy

100% client-side processing
No data transmitted to servers
Works offline
Token never stored or logged
Safe for production tokens

Enter JWT Token:

Sample data

Decoded Token

Status:

VALID

Header (Algorithm & Type)

{
    "alg": "HS256",
    "typ": "JWT"
}

Payload (Claims Data)

{
    "sub": "1234567890",
    "name": "John Doe",
    "admin": true,
    "iat": 1516239022,
    "exp": 1916239022
}

Signature (Encoded)

x8gG_dpH8JmKr5GpfJUKXBuR3F8y4K5gT4OsAFp9s3k

Signature cannot be verified without the secret key or public certificate.

Claims Information

Algorithm :HS256

Type :JWT

Subject (sub) :1234567890

Issued At (iat) :1/18/2018, 2:30:22 AM

Expires At (exp) :9/21/2030, 6:37:02 PM

JWT decoding helps developers debug authentication issues, inspect claims like sub, aud, iss, exp, and understand how applications identify users across APIs and services.

Report Problem