Free Online JWT Decoder / Inspector

Decode and verify JSON Web Token headers, payloads, and signatures with our free online JWT decoder / inspector. Complete client-side tool with no server storage.

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1 How to Use the JWT Decoder / Inspector

Paste your JWT token into the text area (the full token with three parts separated by dots).
Click the 'Decode' button to instantly view the decoded Header, Payload, and Signature sections.
Use the 'Copy Result' button to copy the entire decoded output to your clipboard, or 'Clear' to reset.

What is a JWT Decoder / Inspector?

A JSON Web Token (JWT) is a compact, URL-safe token that consists of a header, a payload, and a signature. Our free online JWT decoder / inspector parses the base64-encoded sections and displays them in a human-readable JSON format, making it easy for developers and security professionals to inspect the token's contents without writing any code. All processing happens entirely in your browser — your token is never sent to a server, ensuring complete privacy and security.

Using an online JWT decoder / inspector is essential for debugging authentication flows, verifying token claims, and understanding the structure of JWTs used in modern web applications. Whether you're testing an OAuth2 implementation, checking expiration dates, or auditing token integrity, this tool provides instant, visual access to every part of the JWT. It's a must-have for any developer working with APIs, single sign-on (SSO), or identity management.

Key Features & Benefits

Client-Side Privacy: All JWT decoding is performed directly in your browser using JavaScript; your tokens are never transmitted or stored on any server.
Instant JSON Formatting: Decoded header and payload are displayed as beautifully indented JSON, making it easy to read nested objects and arrays.
Copy Decoded Output Easily: One-click copy button allows you to quickly copy all decoded sections (header, payload, signature) to your clipboard for further analysis.
Clear and Reset: Quickly clear the input and results with a single button, so you can inspect multiple tokens in rapid succession.

Frequently Asked Questions

What is a JWT decoder / inspector?

A JWT decoder / inspector is an online tool that parses a JSON Web Token and displays its three components — header, payload, and signature — in a readable, structured format. It helps developers verify token contents for debugging and security review.

Is my JWT data safe when using this free online JWT decoder?

Yes, absolutely. All decoding is done client-side in your browser using JavaScript. The token you paste never leaves your computer. There is no server-side processing, and no data is stored or logged by this tool.

Can this tool verify the signature of a JWT?

This JWT decoder / inspector extracts and displays the signature portion, but it does not verify cryptographic validity. For signature verification, you would need the secret or public key corresponding to the signing algorithm (HS256, RS256, etc.).

What does the header of a JWT contain?

The JWT header typically contains two fields: 'alg' (the signing algorithm, e.g., HS256 or RS256) and 'typ' (the token type, usually 'JWT'). Some tokens may include additional custom fields.

What kind of payloads can a JWT have?

The JWT payload contains claims, which are statements about an entity (typically the user) and additional metadata. Standard claims include 'iss' (issuer), 'sub' (subject), 'aud' (audience), 'exp' (expiration), 'nbf' (not before), and 'iat' (issued at). Custom claims are also common.

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