Adempiere is the open source alternative to Compiere and is community oriented. There are fewer options but all of them are free. Adempiere offers more than the free community edition of Compiere.
Adempiere was created after a split between the developers of Compiere. Progress is slower for Adempiere but you are not locked into commercial contracts with ongoing costs. Download Adempiere from adempiere.com.
Adempiere contains ERP, Enterprise Resource Planning, CRM, Customer Relationship Management, and Supply Chain Management functions.
As of April 2010, the Adempiere online documentation is extensive plus there area couple of published books. If you want to read about the product without sitting at your computer, buy one of the books.
In April 2007, Adempiere was the third most popular download from Sourceforge, the world's most popular Web site for open source projects. Adempiere is the most popular ERP and CRM of those on Sourceforge. Sourceforge popularity can be influences by publicity, the
buzz surrounding a project, and a new release can push up the download frequency for a couple of months.
Adempiere has the advantage of ERP and CRM in one application complete with POS and warehouse distribution. Adempiere attracts people who want some combination of those features or who have heard of Compiere but do not want to be locked into a software contract. People with a PHP or Web development background will look for something easier to use, modify, extend, and integrate with their other PHP and Web based applications.
Read about Adempiere then, if you have people skilled with Java, consider using Adempiere and contributing to the Adempiere project. If you really like Compiere in some of the advanced manufacturing areas, you are stuck with Compiere and a commercial license. For everyone else, choose regular PHP base ERP and CRM.