flask-apispec is a lightweight tool for building REST APIs in Flask. flask-apispec uses webargs for request parsing, marshmallow for response formatting, and apispec to automatically generate Swagger markup. You can use flask-apispec with vanilla Flask or a fuller-featured framework like Flask-RESTful. flask-apispec generates Swagger markup for your view functions and classes. By default, Swagger JSON is served at /swagger/, and Swagger-UI at /swagger-ui/.