Techniques are described for using a single application to interact with multiple separate realms simultaneously while maintaining data security boundaries. For example, a web browser may be used to access and interact with the multiple separate secure realms while maintaining data security boundaries between the systems. Multiple concurrent sessions may be established for a user between the web browser and multiple realms. Separate sets of security credentials (e.g., credentials used for authentication and authorization purposes) may be used to establish the sessions and for operations performed in the realms via the sessions. The application can also execute logic (e.g., via machine-executable code or instructions) for automating operations performed in the realms, such as, automating the initiation of a certain operation in one realm based upon a response received from another realm, causing operations to be initiated in two different realms such that the operations overlap in the time; and the like.