Before the software analysis, I want to write a text about this market ... there are many solutions, but I think they all focus on their clients and it may be difficult to choose one for a group like us, because each application is very subjective. ... It depends on whether you prefer a code or a design ...
On the other hand, I analyze 3 ERP and 2 only for invoices ....
ERPNext is a free and open-source integrated Enterprise Resource Planning (ERP) software developed by Frappé Technologies Pvt. Ltd. and is built on MariaDB database system using a Python based server-side framework.
ERPNext is an alternative to NetSuite and QAD, and similar in function to Odoo (formerly OpenERP), Tryton and Openbravo.
We can use only for invoices disabling other modules or we can try to use like a ERP, having CRM, Project Manager and Invoices...
Odoo is a suite of web based open source business apps
The main Odoo Apps include an Open Source CRM, Website Builder, eCommerce, Warehouse Management, Project Management, Billing & Accounting, Point of Sale, Human Resources, Marketing, Manufacturing, Purchase Management, ...
Odoo Apps can be used as stand-alone applications, but they also integrate seamlessly so you get a full-featured Open Source ERP when you install several Apps.
Started to develop on 2005 and now is very matured software and with a good community developers
We can use like a completly enviroment... databases, projects, shops, kanban and accounting... and maybe focus on develop our style.
Aplicación de tres capas licenciado en GPL-3, escrito en lenguage Python y usa PostgreSQL como base de datos.
Es el núcleo base de complejas soluciones empresariales que es modular, escalable y seguro. Ofrece todas las funcionalidades necesarias de una plataforma de aplicaciones completa: persistencia de datos, extensa modularidad, administración de usuarios, flujos de trabajo y motores de reportes, servicios web e internacionalización. Se constituye por tanto en una plataforma de aplicación completa que puede emplearse para cualquier propósito relevante.
Fork from tyniERP then recall, Odoo is a matured project
Although Tryton's modularity make it customizable for almost any business need, it comes with batteries included for trade, manufacturing and project management companies.