We are running a service called the “Sync Core” that sits between your sites and handles all the heavy lifting. You can also host this Sync Core yourself e.g. because your sites are in a private network or you must follow very strict data protection policies that don’t allow SaaS providers. The technical documentation for the Sync Core is available here, including the technical requirements. On-premise hosting is significantly more expensive and requires more work from your end than using our cloud service so we recommend using our cloud service where possible. Please reach out to us if you would like to learn more about on-premise hosting.