The Open Unified Process (OpenUP) is a part of the Eclipse Process Framework (EPF), an open source process framework developed within the Eclipse Foundation. Its goals are to make it easy to adopt the core of the RUP / Unified Process.
The OpenUP began with a donation to open source of process content known as the Basic Unified Process (BUP) by IBM. It was transitioned to the Eclipse Foundation in late 2005 and renamed OpenUP/Basic in early 2006. It is now known simply as OpenUP.
OpenUP preserves the essential characteristics of RUP / Unified Process, which include iterative development, use cases and scenarios driving development, risk management, and architecture-centric approach. Most optional parts of RUP have been excluded, and many elements have been merged. The result is a much simpler process that is still true to RUP principles.
OpenUP targets small and collocated teams interested in agile and iterative development. Small projects constitute teams of 3 to 6 people and involve 3 to 6 months of development effort.
Known uses 
- The Dutch University of Groningen and the Swedish Linnaeus University offer students a collaborative course called ISEP (International Software Engineering Project) in which they heavily use Open Unified Process (OpenUP).