Hi @alko13 , it best fits on the midtier. Having said that, when comparing Engage Direct to other 9.4 based applications, much of the solution is cloud based (for example the UI, identity, authentication authorisation, scheduling as a few examples). Consequently much of the traditonal 9.4 workload is not using the main components of 9.4 for the heavy work, but rather a very light purpose. We find many installations are co-locating all 3 tiers because metadata and midtier are so lightly used or perhaps on 2 tiers not 3. The architecture decisions will depend on your implementations usage, workload and organisation's IT standards.