As defined by the Velocity Network Foundation, a piece of technology, like a gateway, that serves as the interface to the distributed ledger. In the case of Velocity Network Foundation, the CA is a free/open piece of software supplied for access; while the CA is not required to interface with the Velocity Network distributed ledger, the free tool is recommended to minimize time and expense for any entity wishing to anchor verifiable credentials to the Network—the CA removes the need for organizations to build their own network-compliant Agents.