Methods and systems are disclosed for developing a software application through requirements specification, design, effort estimation, assigning and tracking work items, development, testing, collaboration and project management. The system is structured as an integrated software development system allowing for structured, systematic and user friendly set up of requirements specification (including workflow, user interface, business rules and integrations), technical design for UI features and integrations using design patterns, automated effort estimation, automated story card and task creation. The system also provides a novel, audio-video playback capability for workflow visualization. Further, the system provides visual depiction of defects and changed items side-by-side with requirements, as well as predictive modeling of defects that allows for forecasting of defect completion rate. In the preferred embodiment, the system is delivered as a multi-tenant Software as a Service.