Dolibarr - Dolibarr ERP CRM is an Open Source software package for small, medium or large companies, freelancers or foundations to manage business. It's a PHP project built by modules addition (invoice, proposal, contact, stock, order, hr, agenda. .
Odoo - An all-integrated business app suite to unleash your growth potential.
ERPNext - The ERP Software that helps you take full control of your business. ERPNext is both powerful and easy to use.
Infor ERP - An ERP suite for the manufacturing & distribution industries
Adempiere - ADempiere is a commons-based peer-production of Open Source ERP Applications.
BlueSeer - BlueSeer is the best ERP software for your business requirements because it comes with no trial version, and it is completely free to use.