Postman

In current web development most communication between systems is done using API. In most cases it is REST API.

When working with external API or even when we need to set API for somebody else it would be great to have some good tool for REST API testing. And here comes Postman.   

Postman is free tool for REST API testing, with many functions, easy GUI, and ready for automation testing. Many web developers already use this tool (in example me) and I recommend you to test and maybe you too will start using it in you current work.

External links:
getpostman.com -> website where you can get postman tool