PyJWT is a Python library that allows developers to encode and decode JSON Web Tokens (JWTs). JWTs are a compact, URL-safe means of representing claims to be transferred between two parties. JWTs can be used to authenticate and authorize users, and to transmit information securely between systems. PyJWT provides a simple API that makes it easy to work with JWTs in Python.

PyJWT is built on top of the Python cryptography library, which provides cryptographic primitives and protocols. PyJWT supports various algorithms for signing and encrypting JWTs, including HMAC, RSA, and ECDSA. PyJWT also supports the JSON Web Encryption (JWE) and JSON Web Key (JWK) standards, which provide a way to securely exchange encryption keys over the internet.

PyJWT is useful for a wide variety of applications, including web applications, mobile applications, and microservices. It can be used for authentication and authorization, secure communication, and data transmission. PyJWT is compatible with most Python web frameworks, including Django, Flask, and Pyramid.