There are a couple of options for exporting candidate data from Greenhouse Recruiting to your external HRIS.
Custom integration via 'candidate hired' web hook
A 'candidate hired' web hook can trigger as soon as a person clicks Mark Candidate as Hired in Greenhouse Recruiting. The web hook payload contains all application, candidate, job, and offer data needed to kick off or complete the hire business process in your HRIS.
You must use a listener service to receive the 'candidate hired' web hook.
For more information, check out the following resources:
Custom integration via Harvest API
Your organization can use middleware to poll Greenhouse Recruiting for hired candidate data on a scheduled basis, and use the data returned to kick off or complete the hire business process for each of those candidates in your HRIS. Read more about candidate export via API here: API approach to candidate export integration.
Your organization must use middleware to build this integration.
If you would like to further discuss hire integration options, contact Greenhouse Technical Support or your account manager.