Using the SharePoint REST API can be sometime a bit of a pain. Good to have some tools at hand that make life more easy. With the SharePoint 2013 Search Tool you learn how to build an HTTP POST query, and how the different parameters should be formatted.
After running the query, you can view all the different result types returned, e.g. Primary Results, Refinement Results, Query Rules Results, Query Suggestions and the actual raw response received from the Search service.
SharePoint 2013 On-Premise and Office 365 are both supported.
To download visit the project page at Codeplex: