Odoo, formerly known and OpenERP and TinyERP, is an open source ERP and CRM vendor that has been steadily growing in popularity since its launch in 2005. It comes with an impressive set of tools and Odoo reviews are overwhelmingly positive. There are a couple of drawbacks to Odoo. First, Odoo mobile apps are created by Odoo partners, rather than the company itself, so they can be rather confusing. Second, while Odoo comes with two free users, you have to pay for each additional user and each additional app (module) 12 euros per month. That gets to be expensive fast. So, if you are looking for a free OpenERP alternative, Bitrix24 is what you need.
Using Bitrix24 as Odoo alternative
* Please note that the information may have changed since the publication. For current prices and features please visit Bitrix24 pricing page.