Postman is a really useful tool if you building and testing APIs. More than 3 000 developers love that platform because it makes work so much easier, complete and accurate. It has a Postman free app for Mac, Windows and Linux, and a paid version for enterprises that can be used for monitoring, API testing and documentation.
Free online tool to test APIs and autogenerate documentation
Swagger Inspector is a free cloud-based API testing and documentation tool to simplify the validation of any API and generate its corresponding OpenAPI documentation. Swagger Inspector is part of the Swagger family of API developer tools.
The Swagger family of tools is brought to you by SmartBear Software.