Top 5 hierarchical-state-machine open source projects

A lightweight, object-oriented finite state machine implementation in Python with many extensions

QM model-based design tool and code generator based on UML state machines

A rust implementation of statecharts: hierarchical, reactive state machines

KStateMachine is a Kotlin DSL library for creating finite state machines (FSM) and hierarchical state machines (HSM).

A Hierarchical State Machine Framework in C++