SpiffWorkflow is a pure Python library for executing BPMN 2.0 and DMN 1.x workflows. It provides a full-featured workflow engine that parses BPMN XML diagrams into process specifications, manages task state and execution (including script tasks, service tasks, user tasks, gateways, events, and subprocesses), and supports serialization/deserialization for long-running workflow persistence with version migration. The architecture is modular—separating parsers, task specifications, script engines, and serializers—and is designed to be embedded into applications (e.g., SpiffArena, CLI examples). The library includes extensive test coverage of BPMN control-flow patterns, boundary events, timers, multi-instance, call activities, and DMN decision tables. External dependencies are minimal (lxml, pytz, python-dateutil). Key entry points are the BpmnWorkflow class for runtime, the BpmnParser / BpmnDmnParser for model ingestion, and the PythonScriptEngine for executing scripts. The repo is a hybrid of a core library and extension modules (Camunda compatibility, Spiff custom extensions), but it is strictly a software library, not an application or data-research project.