What is JWT エンコーダー / デコーダー?

A tool for encoding and decoding JWT (JSON Web Tokens). JWT is a widely used token format for web authentication and information exchange. You can separate and inspect the header, payload, and signature of a token.

How to Use

1. In decode mode, paste a JWT token string to automatically separate the header and payload.
2. In encode mode, enter header and payload in JSON format.
3. Optionally enter a secret key to generate a signed token.
4. Copy the result for your use.

Key Features

• JWT token decoding and structure analysis
• JWT token encoding (with or without signature)
• Separate display of header, payload, and signature
• Formatted JSON output for readability

Tips

• A JWT consists of three parts separated by dots: Header.Payload.Signature.
• JWT payloads are only Base64-encoded, not encrypted — never put sensitive information in them.
• Check standard claims like expiration time (exp) and issued at (iat) to validate tokens.