PaPy is a framework to construct and execute bioinformatic pipelines (flow-charts) of arbitrary tasks in parallel, either locally, using multi-processing or multi-threading, or remotely, using remote procedure calls (as implemented in the Python library RPyC). The goal is to enable users to efficiently and reproducibly create clean, modular workflows for the execution of ad hoc computing grids consisting of local workstations, remote desktops/servers, clusters, or any aribitrary mixture of the above compute resources.