Yes, a version of EasyCatalog is available for InDesign Server. It’s a version of EasyCatalog without a user interface, so a script is used to drive EasyCatalog. When using EasyCatalog for Server, it’s typical to have least one desktop license as this is required to edit templates, libraries, etc.
Multi-instance servers are also supported, data sources can be shared amongst all instances, or each instance can have its own.
Please contact your local reseller for pricing.