Explanation
The Add-On Builder is available from SplunkBase, which is the official source of apps and add-ons for the Splunk platform. SplunkBase allows you to browse, download, and install apps and add-ons that are compatible with your Splunk deployment. You can also upload and share your own apps and add-ons with the Splunk community. The Add-On Builder is a Splunk app that helps you build and validate technology add-ons for your Splunk Enterprise deployment. Technology add-ons are specialized add-ons that help to collect, transform, and normalize data feeds from specific sources in your environment. The Add-On Builder guides you through the process of creating an add-on, following best practices and naming conventions, maintaining CIM compliance, and testing and validating the add-on1. The Add-On Builder is not available from GitHub, www.splunk.com, or the ES installation package. References = Splunk Add-on Builder | Splunkbase

Splunk Add-on Builder | Splunkbase