Answer:   1. Dolibarr : It is an open source solution for small and midsize businesses. It offers such services as keeping track of invoices, orders, contracts, and payments and supporting electronic systems. It provides businesses with an online demo and add-ons store where you can buy full version with more features.
2. ERPNext : It is a popular open source project that was created in 2014 to replace an expensive ERP implementation. It’s perfect for small and midsize businesses and has all necessary modules for project management, accounting, managing inventory, sales, purchase. It’s easy in use, has a clear interface and offers a set of fields that you can fill with information.
3. Apache OFBiz : It enables organizations to customize the ERP to their needs and it’s perfect for midsize or large businesses that have the most internal development resources to integrate it within business processes. It has Modules that provide tracking for manufacturing, accounting, inventory management, HR, CRM, and e-commerce.