What is the primary function of JWT in API security?

The primary function of JSON Web Token (JWT) in API security is to securely transmit information between parties. JWTs are compact, URL-safe tokens that can represent claims to be transferred between a client and a server. The structure of a JWT includes a header, payload, and signature, allowing for the authentication and verification of the sender's identity while ensuring that the message cannot be tampered with in transit.

Using JWTs, information such as user identities and permissions can be effectively conveyed, allowing servers to authenticate users and authorize access to resources without the need for constant re-validation against a database. This leads to more efficient and streamlined API interactions.

While JWTs may relate indirectly to other aspects such as data encryption and endpoint validation, their core purpose is the secure transmission of claims and information, making effective use of the signing process to ensure trustworthiness and integrity.