JWT Decoder - Inspect Tokens Instantly

How the JWT Decoder Works

1. 01Paste your JWT token into the input field
2. 02The decoder splits the token into its three parts: header, payload, and signature
3. 03View the decoded header (algorithm, type) and payload (claims, expiration) as formatted JSON
4. 04Check the expiration timestamp to see if the token is still valid

Understanding JSON Web Tokens

JWTs consist of three Base64-encoded parts separated by dots: header, payload, and signature. The header specifies the signing algorithm (usually HS256 or RS256). The payload contains claims like user ID, roles, and expiration time (exp). Important: decoding a JWT does NOT verify its signature - anyone can read a JWT's contents. Never store sensitive data in JWT payloads, and always validate the signature server-side.

When to Use the JWT Decoder

Use this decoder when debugging authentication and authorization issues in web applications. Inspect JWTs from login responses, API headers, or browser cookies to check claims, roles, expiration times, and issuer information. It is especially useful when troubleshooting why an API returns 401 or 403 errors.

Common Use Cases

• ·Debugging 401/403 errors by inspecting token claims, roles, and expiration times
• ·Verifying OAuth/OIDC token contents during SSO integration development
• ·Checking what user data is exposed in JWT payloads for security audits
• ·Inspecting refresh tokens and access tokens to understand session management flows → JSON Formatter & Validator

Expert Tips

• ✻Never store sensitive data (passwords, credit card numbers) in JWT payloads - they are encoded, not encrypted
• ✻Check both the 'exp' (expiration) and 'nbf' (not before) claims to understand the token's valid time window
• ✻In browser DevTools, find JWTs in the Application tab under Cookies or Local Storage, or in the Network tab under Authorization headers

Frequently Asked Questions