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JWT Decoder Online

Decode and inspect JSON Web Tokens (JWT) client-side. Fast, secure, and fully private.

Encoded JWT Token
Header: Algorithm & Token Type
Payload: Claims & Data
Signature (HMAC or RSA hash)
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About This Tool

JWT Decoder

Decode any JSON Web Token (JWT) to instantly read its header, payload, and expiry — without needing a secret key.

Why Use This Tool?

  • Debug JWT tokens during API development or authentication testing
  • Read token payload to check user roles, permissions, and expiry time
  • Verify token structure and claims without needing a backend
  • Used by backend developers, QA engineers, and security testers
  • Inspect tokens from OAuth, Firebase, or any JWT-based authentication system

Overview

JSON Web Tokens (JWTs) are the most widely used mechanism for authentication and information exchange in modern web applications and APIs. A JWT consists of three Base64-encoded parts separated by dots: a Header (algorithm and token type), a Payload (claims/data), and a Signature (for verification). While the signature requires the secret key to verify, the header and payload can be decoded and read by anyone with the token — they are encoded, not encrypted. Our JWT Decoder does exactly this: paste any JWT and instantly read its decoded header and payload in a formatted, human-readable JSON view. You can immediately see the user ID, roles, permissions, expiry time (exp), issued-at time (iat), and any other claims embedded in the token. This is invaluable for debugging authentication issues, testing API integrations, understanding what data your auth system provides, and learning how JWT-based authentication works.

How to Use

  • 1

    Paste Your JWT Token

    Copy the JWT string (it looks like xxxxx.yyyyy.zzzzz) from your API client, browser DevTools, or auth system and paste it in the input field.

  • 2

    Decode Instantly

    The header, payload, and signature sections are decoded and displayed automatically.

  • 3

    Read the Payload

    View the decoded payload JSON to see user data, roles, permissions, expiry time, and other claims.

  • 4

    Check Expiry

    The "exp" claim shows the token expiry time. Our tool converts this Unix timestamp to a human-readable date and time.

  • 5

    Check Token Structure

    Verify the token has exactly three parts separated by dots. Malformed JWTs will show an error.

Frequently Asked Questions

Only paste JWTs in testing environments. Our tool runs entirely in your browser — no token is sent to any server. However, JWTs for production sessions should never be shared.
Verifying the signature requires the secret key, which should never be shared. This tool only decodes the header and payload without signature verification.
"exp" (expiration time) is a Unix timestamp indicating when the token expires. After this time, the token is invalid and must be refreshed.
"iat" (issued at) is the Unix timestamp of when the token was created by the server.
JWTs are encoded (not encrypted) for transmission convenience. The signature ensures they cannot be tampered with, but the content is readable by anyone with the token. Do not put sensitive data in JWT payloads.

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