The implementation of CAltAlt uses several off-the-shelf planning software packages. Figure 9 shows a diagram of the system architecture for CAltAlt and . While CAltAlt extends the name of , it relies on a limited subset of the implementation. The components of CAltAlt are the IPC parser for PDDL 2.1 (slightly extended to allow uncertain initial conditions), the HSP-r search engine , the IPP planning graph , and the CUDD BDD package  to implement the labels. The custom parts of the implementation include the action representation, belief state representation, regression operator, and the heuristic calculation.
The implementation of is very similar to CAltAlt aside from the search engine, and state and action representation. also uses the IPP source code for planning graphs. uses modified LAO*  source code from Eric Hansen to perform AO* search, and CUDD  to represent belief states and actions. Even with deterministic actions it is possible to obtain cycles from actions with observations because we are planning in belief space. constructs the search graph as a directed acyclic graph by employing a cycle-checking algorithm. If adding a hyper-edge to the search graph creates a cycle, then the hyper-edge cannot represent an action in a strong plan and is hence not added to the graph.