100% Client-Side Processing
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JWT Decoder
Decode JSON Web Tokens (JWT) in your browser. View the header and payload, pretty-print JSON claims, and learn about token structure.
JWT Token
Header
Payload
Signature (raw base64url)
How It Works
JWT (JSON Web Token) consists of three base64url-encoded parts: header.payload.signature. Our tool decodes the header and payload to reveal the JSON structure and claims.
Step-by-Step Process:
- Paste your JWT token into the input field
- The tool automatically splits the token into header, payload, and signature
- View the decoded JSON for header and payload sections
- Inspect claims like iss, sub, aud, exp, and custom fields
Use Cases
JWT tokens are widely used for authentication and authorization in modern web applications and APIs.
API Authentication
Decode access tokens to understand user permissions, scopes, and expiration times in REST APIs and microservices.
Debugging & Development
Inspect JWT structure during development to verify claims, check expiration times, and troubleshoot authentication issues.
Security Analysis
Analyze JWT tokens to understand their structure, identify security claims, and verify proper implementation patterns.
Token Validation
Check token expiration, issuer information, and audience claims before implementing server-side verification.
Privacy Promise
JWT tokens often contain sensitive user information and permissions. Our decoder ensures complete privacy protection.
🔒 Your data never leaves your browser - 100% client-side processing guaranteed
Frequently Asked Questions
Does this tool verify JWT signatures?
No, this tool only decodes the header and payload. Signature verification requires the secret key or public key and should be done server-side with proper JWT libraries.
What's the difference between Base64 and Base64url?
JWT uses Base64url encoding, which replaces + with - and / with _ to make tokens URL-safe. It also omits padding characters (=) that standard Base64 uses.
Is it safe to decode JWT tokens here?
Yes, all decoding happens locally in your browser. No tokens are sent to our servers. However, be cautious with production tokens containing sensitive data.
What are the common JWT claims?
Standard claims include iss (issuer), sub (subject), aud (audience), exp (expiration), iat (issued at), nbf (not before), and jti (JWT ID). Custom claims can also be included.
Why can't I see the signature content?
The signature is a cryptographic hash that can't be meaningfully decoded. It's used to verify the token's integrity and authenticity using the appropriate key.