The Access/CPN framework: A tool for interacting with the CPN tools simulator Coloured Petri nets (CP-nets or CPNs) is a widely used formalism for describing concurrent systems. CPN Tools provides a mature environment for constructing, simulating, and performing analysis of CPN models. CPN Tools also has limitations if, for example, one wishes to extend the analysis capabilities or to integrate CPN models into external applications. In this paper we present Access/CPN, a framework that facilitates such extensions. Access/CPN consists of two interfaces: one written in Standard ML, which is very close to the simulator component of CPN Tools, and one written in Java, providing an object-oriented representation of CPN models, a means to load models created using CPN Tools, and an interface to the simulator. We illustrate Access/CPN by providing the complete implementation of a simple command-line state space exploration tool