Automatic analysis and recognition of documents is a complex task. Substantial research effort has therefore been spent addressing sub-tasks of manageable size. The solutions, however, have to be integrated into a comprehensive engine. Following the idea of a toolbox, a software architecture has been developed that enables various tools to be combined into a network of co-operating recognition algorithms. Distributing the tools on a number of processors improves overall performance by parallel execution. The configuration of the tools as well as the connections between them can easily be modified, even at run-time. Simple, interactive access to the various parameters and intermediate results of an algorithm aids the development and evaluation of experimental systems. The modular approach also facilitates extension of existing systems by the integration of novel methods. DART, the Distributed Asynchronous Recognition Toolbox architecture, realises these features.