Toools

🔐 What is a JWT?

A JSON Web Token (JWT) is a compact and self-contained way to transmit information between parties securely using a JSON object. It is commonly used for authentication and authorization in modern web applications.

🧠 Why Decode a JWT?

• To inspect the contents (claims) of the token
• To debug authentication or authorization issues
• To verify expiry (`exp`), issuer (`iss`), subject (`sub`) fields
• To understand what data is being passed between services

⚙️ How This JWT Decoder Tool Works

Simply paste your JWT into the input box. The tool instantly decodes the header and payload using base64 URL decoding and displays them in JSON format. The signature is displayed as a third, separate section.

• Paste a JWT (must contain 3 parts: header.payload.signature)
• The tool validates the structure automatically
• Decoded JSON for header and payload are shown below
• You can copy each part individually with a single click

📋 What Can You Decode?

• Access tokens (from OAuth2 or OpenID Connect providers)
• Session tokens issued by your backend
• ID tokens from services like Auth0, Firebase, AWS Cognito

🧾 Common JWT Fields

• iss: Issuer
• sub: Subject (user ID)
• exp: Expiration time (in seconds)
• iat: Issued at
• aud: Audience
• nbf: Not before

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