Odoo is an all-in-one management software that offers a range
of business applications that form a complete suite of enterprise
management applications. The Odoo solution is ideal for SMEs,
but fits both small and large companies alike. Odoo is an all-in-one
business software capable of covering all business needs, including CRM,
Website/e-Commerce, billing, accounting, manufacturing, warehouse- and
project management, and inventory, all seamlessly integrated.
Odoo offers three separate versions of the solution; Odoo Enterprise, Odoo Online SaaS (Software as a Service) version, and the Odoo Community version. The Enterprise version is self
hosted, it includes all the apps, and the pricing starts at $360 per
user per year, with a minimum of 5 users. The Odoo Online version is hosted on a cloud,
and the first app is offered for free as a standalone app for unlimited
users. After the first app, there is a fixed monthly subscription fee
for the apps used and the number of users. The Community version is the open source version. The Source code for the OpenObject framework and core ERP (Enterprise Resource Planning) modules is curated by the Belgium-based Odoo S.A. The last fully featured Open Source version was 8.0 (LTS), available on GitHub under AGPLv3. Odoo is the most popular open source ERP system
Reference : https://en.wikipedia.org/wiki/Odoo