Developer Tools
Security ToolsJWT Decoder
Decode and inspect JSON Web Tokens. No data is sent to our servers - all decoding happens in your browser.
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About JWT Decoding
What is a JWT?
JSON Web Token (JWT) is an open standard (RFC 7519) that defines a compact and self-contained way for securely transmitting information between parties as a JSON object. This information can be verified and trusted because it is digitally signed.
JWT Structure
- Header - Contains the type of token and the signing algorithm
- Payload - Contains the claims (user data and metadata)
- Signature - Verifies the token hasn't been altered
Common Use Cases
- Authentication and authorization systems
- Secure information exchange between parties
- Single Sign-On (SSO) implementations
- API authentication
- Stateless session management
- Access token validation
JWTs are commonly used in web applications, microservices, and mobile apps for securely transmitting information that can be verified and trusted.
Frequently Asked Questions
What is a JWT token and why would I need to decode it?
JWT (JSON Web Token) is a secure way to transmit information between parties. You might need to decode JWT tokens to inspect their contents, verify claims, check expiration times, or debug authentication issues in your applications.
Is it safe to paste my JWT token into this tool?
Yes, this tool works entirely in your browser using JavaScript. No data is sent to our servers, ensuring your JWT tokens remain private and secure. All decoding happens locally on your device.
What information can I see in a decoded JWT?
A decoded JWT typically shows three parts: the header (algorithm and token type), the payload (claims like user ID, expiration, roles), and the signature verification status. This helps you understand what data the token contains.
Can this tool verify if my JWT signature is valid?
This tool can decode and display JWT components, but signature verification requires the secret key or public key used to sign the token. The tool will show the signature section, but actual verification should be done on your server with the appropriate keys.
What does it mean if my JWT token appears to be expired?
JWT tokens often include an "exp" (expiration) claim. If the current time is past this expiration timestamp, the token is considered expired and should not be accepted by services. You'll need to obtain a new token.
Why am I getting an "Invalid JWT format" error?
JWT tokens must have exactly three parts separated by dots (header.payload.signature). The error occurs if your token is malformed, incomplete, or not a valid JWT. Check that you've copied the complete token without extra spaces.
Can I decode JWT tokens from any authentication system?
Yes, this tool can decode any standard JWT token regardless of which system generated it (Auth0, Firebase, custom servers, etc.). JWT is a standardized format, so all compliant tokens can be decoded using this tool.
What's the difference between the header, payload, and signature sections?
The header contains metadata like the signing algorithm. The payload contains the actual claims and data (user info, permissions, expiration). The signature is used to verify the token hasn't been tampered with and was issued by a trusted source.
How do I copy the decoded information for use in other tools?
Each section (header, payload, signature) has its own copy button. Click the "Copy" button next to the section you want to copy. The information is copied as formatted JSON that you can paste into other tools or applications.
Can this tool help me debug authentication issues?
Yes, by decoding JWT tokens you can verify claims like user permissions, check expiration times, inspect issuer information, and ensure the token contains the expected data. This is invaluable for troubleshooting auth problems.
What should I do if the payload shows unexpected or missing claims?
If claims are missing or incorrect, the issue is likely with the token generation process on your authentication server. Check your server configuration, user data, or token generation logic to ensure proper claims are being included.
Does this tool work with refresh tokens and access tokens?
Yes, this tool can decode any JWT-formatted token, including access tokens, refresh tokens, and ID tokens. However, not all authentication systems use JWT format for all token types, so some tokens might not be decodable if they use a different format.