This document discusses ensuring the sustainable development of open source products. Open source software sustainability is pursued by creating value for all stakeholders. Some key ways to sustain open source product development include corporate sponsorship and generating revenue from services, complementary products, and support/training. While open source software is initially free, 3% of users on average become paying customers. A case study of the open source product Joget Workflow shows how it was able to sustain development through consulting, training, implementation services, and an enterprise edition to generate over $500k in funding in under 2 years.