What is a JSON Web Token (JWT)?
JWTs are an open, industry-standard method for representing claims securely between two parties. They are widely used for authentication and information exchange in microservices and single-page applications.
Understanding the JWT Structure
A JWT consists of three parts separated by dots:
- Header: Typically consists of the type of token and the signing algorithm.
- Payload: Contains the "claims" or the data you want to transmit.
- Signature: Used to verify that the sender of the JWT is who it says it is.
The Security Risks of JWT
While powerful, JWTs are not encrypted by default—they are only encoded (Base64). If a developer stores sensitive data like passwords inside the payload, anyone who intercepts the token can read it using a JWT Decoder.
Best Practices for API Security
- Always use HTTPS to prevent token interception.
- Keep your secret keys safe and rotate them periodically.
- Set appropriate expiration times for your tokens.