JWT Decoder
Decode and inspect JSON Web Tokens securely without sending them to a server.
What is the JWT Decoder?
The JWT Decoder is a tool designed to decode JSON Web Tokens (JWT) locally in your browser. It parses the base64-encoded strings and breaks them down into readable JSON objects representing the Header and Payload.
JWTs are commonly used for authentication and authorization in web applications. This tool allows developers to inspect the contents (claims) of a token—such as user roles, expiration times, and issuers—without needing any backend logic.
How to use the JWT Decoder
- 1Paste your JWT string into the input text area.
- 2The tool will instantly decode the token and display the Header and Payload as formatted JSON in the panels below.
- 3Review the decoded claims to verify your authentication token is structured correctly.
Key features
- ⚡ Instant Decoding: No submit buttons—your token is decoded in real-time as you paste it.
- 🔒 Secure & Private: Decoding is performed 100% locally in your browser using standard JavaScript. Your token is never sent to a server.
- 🎨 Formatted Output: Automatically prettifies the Header and Payload JSON for easy reading.
Examples
Decoding an Auth Token
eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9...Displays {"alg": "HS256", "typ": "JWT"} in the Header pane.Why use this tool
- Helps debug authentication issues by making token claims human-readable.
- Ensures your sensitive tokens remain private and secure on your own machine.
Frequently asked questions
Is my token safe here?
Yes. The JWT Decoder uses client-side JavaScript to decode the base64 payload. No data is ever transmitted to a backend server.
Can this tool verify the JWT signature?
Currently, this tool only decodes the token so you can view its contents. Signature verification requires a secret key and is best handled by your application server.
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