Odoo is an open source ERP and CRM tool, offered as an integrated suite of applications including modules for project management, invoicing, accounting, inventory management, manufacturing and purchasing. These modules can communicate with each other to exchange information in an efficient and transparent manner. With a simple and intuitive user interface, reminiscent of Google Drive, its robust technical structure offers unparalleled usability that applies to all applications. While there is a limit of free apps, adding new apps is not prohibitive.
Apache OFBiz's suite of business tools is built on a common architecture that allows organizations to customize ERP according to their needs. Therefore, it is best suited for medium to large enterprises with the internal development resources to adapt and integrate with their existing IT and business processes. OFBiz is a mature open source ERP system. Modules are available for accounting, manufacturing, human resources, inventory management, customer relationship management, e-commerce, etc.
BlueSeer is a completely free ERP software package (no key, no test, no registration) for small and medium businesses as well as personal finance. BlueSeer aims to be the first universally free ERP system whose sole purpose is to provide businesses with a free alternative to expensive ERP systems. BlueSeer ERP was developed for manufacturing, storage, and transportation companies who want to customize and manage their own software without the need for high cost proprietary support or proprietary source code difficulties. BlueSeer has the added benefit of being more than an ERP. The customization capability allows BlueSeer to also be used as a custom peripheral application.