Born from the research project Jonas, Petals ESB has undergone many evolutions, parsed throughout, up to now, four major branches.
While the branches 1.x to 3.x were following the same practices and goals, a significant switch in the approach and objectives has been decided for branch 4.x.

This explains why you'll find only navigation for these two branches:

• 3.x for already running projects, including historical clients;
• 4.x for already running projects, including historical clients;
• 5.x recommended since summer 2016 for any new project.

For more information on this, please read Petals blog entry explaining the major differences between Petals ESB3.x and Petals ESB 4.x.