Is the JWT decoder free?

Yes, Attachad's JWT decoder is completely free with no limits or hidden fees. No account or signup required.

How does the JWT decoder work?

Simply paste your JWT token into the input field and the tool will instantly decode it, displaying the header, payload, and signature parts in a readable format.

Does it verify signatures?

This tool decodes and inspects JWT tokens but does not verify cryptographic signatures. For signature verification, you would need the secret key.

JWT DecoderDecode JSON Web Tokens Instantly

Q: What is a JWT?

JWT (JSON Web Token) is an open standard for securely transmitting information between parties as a JSON object. It's commonly used for authentication and authorization.

Q: Is my token data stored?

No, all decoding happens locally in your browser. Your JWT token never leaves your device.

Decode JWT tokens and inspect header, payload, and claims. Perfect for debugging authentication tokens and understanding JWT structure.

✓ Decode Header & Payload✓ Check Expiration✓ Copy Data✓ 100% Free

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JWT Structure

header.payload.signature

Header: Contains algorithm (HS256, RS256) and token type
Payload: Contains claims (sub, name, iat, exp, etc.)
Signature: Verifies token authenticity (not decoded)

Common JWT Claims

What is JWT (JSON Web Token)?

JWT (JSON Web Token) is an open standard (RFC 7519) for securely transmitting information between parties as a JSON object. It's commonly used for authentication and authorization in modern web applications and APIs.

Our JWT decoder helps you inspect and understand JWT tokens by decoding the header and payload sections. All decoding happens locally in your browser — your tokens never leave your device.

JWT Token Structure

A JWT token consists of three parts separated by dots:

Header: Contains the signing algorithm (HS256, RS256) and token type (JWT)
Payload: Contains the claims (user data, permissions, expiration, etc.)
Signature: Verifies the token hasn't been tampered with (requires secret key)

Common JWT Use Cases

🔐 API Authentication

Verify users and authorize API access

🔄 Single Sign-On (SSO)

Share authentication across multiple apps

📱 Mobile Apps

Stateless authentication for mobile backends

🔗 OAuth2 Tokens

Access tokens in OAuth2/OIDC flows

Frequently Asked Questions

What is JWT used for?

JWT is primarily used for authentication and authorization in web applications, APIs, and mobile apps. It allows stateless verification of user identity.

Does JWT decoding verify signatures?

No, this tool decodes and inspects the token content but does not verify cryptographic signatures. Signature verification requires the secret key.

What's the difference between JWT and JWS?

JWT (JSON Web Token) is the standard, while JWS (JSON Web Signature) is the signed version of a JWT. Most JWTs are JWS.

Is my token data secure?

Yes, all decoding happens locally in your browser. Your JWT token never leaves your device.

Can I decode expired tokens?

Yes, decoding works regardless of expiration. You'll see the 'exp' claim and can check if the token is expired.

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