Postman is an API platform that enables developers to design, test, document, monitor, and collaborate on APIs throughout their lifecycle. It provides both a desktop application and web interface for working with HTTP, REST, GraphQL, WebSocket, gRPC, and SOAP APIs. Postman centralizes API development workflows by offering collections to organize requests, environments for managing variables, automated testing capabilities, mock servers, monitoring, and team collaboration features—making it an essential tool for API-first development and quality assurance.