Ecopath with Ecosim (EwE) is a free and open source ecosystem modelling software suite, initially started at NOAA by Jeffrey Polovina, but has since primarily been developed at the formerly UBC Fisheries Centre of the University of British Columbia. In 2007, it was named as one of the ten biggest scientific breakthroughs in NOAA's 200-year history. The NOAA citation states that Ecopath "revolutionized scientists' ability worldwide to understand complex marine ecosystems". Behind this lie more than three decades of development work in association with a thriving network of fisheries scientists such as Villy Christensen, Carl Walters and Daniel Pauly, and software engineers around the world. EwE is funded through projects, user contributions, user support, training courses and co-development collaborations. Per November 2021 there are an estimated 8000+ users across academia, non-government organizations, industry and governments in 150+ countries
In 2013, development efforts were centralized under Ecopath International Initiative, Spain, which coincided with a switch to a community-driven development model overseen by the Ecopath Research and Development Consortium. As the approach does not receive any core funding, the Ecopath with Ecosim approach now relies entirely on user-contributed project funding for continued development and releases.