Documentum functionality is made available through application programming interfaces (API) including web services, WebDAV, FTP, Java, Documentum Foundation Classes, Documentum Query Language (DQL), Web Development Kit API (WDK), SMB/CIFS and CMIS.
Most of the customization in the basic product is done using the DFC (Documentum Foundation Classes), a comprehensive but rather dated (as of 2015) collection of Java APIs.