This paper presents a software package called the "Collective Rhythms Toolbox" (CRT), a flexible and responsive audio-visual interface that enables users to investigate the self-synchronizing behaviors of coupled systems. As a class of multi-agent systems, CRT works with networks of coupled-oscillators and a physical model of coupled-metronomes, allowing users to explore different sonification routines through real-time parameter modulation. Adjustable coefficient matrices allow for complex coupling topologies that can induce a diverse range of dynamic rhythmic states and audio-visual feedback facilitates user engagement and interactive flow. Similarly, several real-time analysis techniques provide the user with visual information pertaining to the state of the system in terms of group synchrony. Ultimately, this paper showcases how parameterizing coupled systems in specific ways allows different computer music and compositional techniques to be carried out through the lens of dynamical systems-based approaches.