Dynamo Application Server (DAS) was a Java EE-conformant application server developed by Art Technology Group (ATG).
Initially Dynamo is intended to be an application server on which ATG product is to be run. Later on ATG dropped plans for development of a separate app server and rather decided to support running ATG on various other application servers.
However Dynamo application server is not completely removed, some components of it still exist in ATG predominantly for enabling the communication with various app servers.