Is it possible to use the Harvest REST API for Check-in? If not, is this planned in future Harvest releases ?
Harvest 14.5.x
As of March 2026, the Harvest REST API does NOT support/allow the check-in function.
Harvest Engineering and Product Management have agreed to take a look at the technical feasibility of adding this capability to the Harvest REST API.
Since this enhancement can be delivered as a patch, the current plan is to release the patch shortly after the release of the next Harvest version (14.6) which is currently scheduled for November 2026 (subject to change).