Navigate to the below URL and Download the latest version of the solution of CRM Rest Builder

For 2015 & 2016 & D365 use the v2.5.0.0 release
For 2011 & 2013 use the v1.5.0.0 release

1) CRM Rest Builder GIT Hub URL
2) CRM Rest Builder Drive  v2.5.0.0 , v1.5.0.0

And follow the below steps

Step 1 - Navigate to your Organisation Settings -> Solutions and click on Import Button

Step 2 - Click on to Browse Button

Step 3 - Navigate to the solution file previously downloaded and click on open and then click on Next

Step 4 - Click on to Import Button

Step 5 - After some time you will see the below success message

Step 6 - Now you will be able to see the CRM Rest Builder Button on the ribbon bar on solutions Click on it

And You are good to go with CRM Rest Builder

Happy CRMing 😊