Venafi Trust Protection Platform 19.2 and up
Venafi MMC Wcf Host: This service is a WCF self-hosted web service used to run the Venafi Code Signing and Venafi Event Viewer MMC snap-ins on the Trust Protection Platform server. This service allows snap-ins run on the server even if IIS is not installed. It listens on port 689 and accepts requests only from localhost, to allow those snap-ins to perform their functions. By default, it stops after 10 minutes of inactivity.
This and other services are covered more in depth here: