It's a REST Client for SharePoint 2013, 2016 and Online. SharePoint end-points can be tested very easily by making GET, POST, UPDATE or DELETE request.
Before using this extension, login or navigate to your SharePoint site, then click on the extension icon. After few moment, you will get some cool UI for making GET, POST, UPDATE or DELETE request.
SP REST Client is free and open source tool. So you are always welcome to contribute here.
Finally, I hope, this tool will be your ultimate REST Client for SharePoint. Please don't forget to rate it if you get any help from it.