Postman is a platform for building, testing, and documenting APIs. You can send HTTP requests, inspect responses, and organize them into collections that can be shared with a team. Environment variables let you switch between development, staging, and production endpoints without editing every request. Automated tests can be written in JavaScript and run as part of a collection.

The platform also supports API mocking, monitoring, and documentation generation. Collections can be published so other developers can try an API without writing code. Postman has become a standard tool in many API development workflows, and the free tier covers individual use and small teams. If you work with REST or GraphQL APIs regularly, it's hard to avoid eventually using it.