Backend API
The original backend API for Nagios XI was designed to query current status and historical information.
Documentation - Backend API Access
Backend REST API
As of Nagios XI 5, a new REST API was introduced. This API allows you to read, write, delete, and update data in the Nagios XI system through commands that are authenticated via Nagios XI API keys.
All of the documentation is available inside of the Nagios XI product via the Help menu. In the left pane you will find the section REST API Docs.
Final Thoughts
For any support related questions please visit the Nagios Support Forums at: