Integration of business functions, from accounting to customer relations management, is becoming part of modern doing business. Improvement of business processes as well as effectivity and effectiveness increase through implementation of certain ERP solutions are becoming motivation factor for companies to start their own business integration. Leading ERP vendors, from SAP and Microsoft to Oracle, although have many advantages, usually have high implementation cost. There are also open source solutions that are, at least on the beginning, free of charge. This paper explains basic ERP terms; from vendors from tier one to open sources solutions and their differences. Special attention is given to open sources solutions such are Odoo and OpenBravo. Additionally, paper presents main characteristics, architecture and used technology of those two ERPs with explanation of main characteristics and differences. In the last part of the paper, there is a comparative analysis of the two open source ERPs as well as recommendation which one is performing better.