JWT Decoder

What is JWT Decoder?

JWT Decoder is a free online tool that allows you to decode and inspect JSON Web Tokens (JWT) instantly. Paste any JWT and see its header, payload, and signature components decoded into readable JSON format, making it easy to debug authentication issues and verify token contents.

Why Would You Need to Decode JWT Tokens?

• Authentication Debugging: Troubleshoot login issues by inspecting token claims and expiration times
• Security Auditing: Verify that tokens contain appropriate permissions and user information
• API Development: Test and validate JWT tokens during API integration and development
• Token Verification: Check token structure, algorithm, and payload before processing
• Learning JWT: Understand how JWTs work by examining their internal structure

How to Decode JWT Tokens - Step by Step

1. Paste Your Token: Copy and paste your complete JWT string into the input field
2. View Decoded Parts: Instantly see the header, payload, and signature sections decoded
3. Analyze Claims: Review standard claims like exp, iat, sub, and any custom claims
4. Check Expiration: Verify if the token is still valid based on its expiration timestamp

Key Features

• Instant Decoding: Decode JWT tokens in real-time as you paste them
• Structured Output: View header and payload as formatted, readable JSON
• Expiration Check: Automatically detect if the token has expired
• Algorithm Detection: See which signing algorithm (HS256, RS256, etc.) was used
• Privacy-Focused: All decoding happens in your browser - tokens are never sent to any server

Tips for Best Results

• Always verify the token source before trusting its decoded contents
• Check the "exp" claim to ensure the token has not expired
• Never share tokens containing sensitive information in public channels

Frequently Asked Questions

What is a JWT token?

A JSON Web Token (JWT) is a compact, URL-safe way to represent claims between two parties. It consists of three parts: a header (algorithm and token type), a payload (claims and data), and a signature (verification). These parts are Base64-encoded and separated by dots.

Can this tool verify JWT signatures?

This tool decodes and displays JWT contents but does not verify signatures, as that requires the secret key or public key used to sign the token. Signature verification should be done server-side with the appropriate keys.

Is it safe to paste my JWT here?

Yes, all decoding happens entirely in your browser. Your token is never transmitted to any server. However, you should still be cautious about sharing tokens that contain sensitive information or are still valid.