Our work on Simple Invoices is driven by the philosophy to create the best invoicing software available by using free and open source software and have alot of fun on the way!
Refer this wiki page for more info but it can be summarised as:
Free software is software that gives you the user the freedom to share, study and modify it. We call this free software because the user is free.
To use free software is to make a political and ethical choice asserting the right to learn, and share what we learn with others. Free software has become the foundation of a learning society where we share our knowledge in a way that others can build upon and enjoy.
For more info have a read up on the Free Software Foundations website http://www.fsf.org/about/what-is-free-software
For Simple Invoices, the “free” in “free software” is used primarily in reference to freedom and not to price - although we are committed to not charging for Simple Invoices. The most important thing about Simple Invoices is not that it is available free of charge, but that it confers rights of software freedom on the people who install and use it. It is those freedoms that enable the Simple Invoices community to grow, sharing its collective experience and expertise to improve Simple Invoices and make it suitable for use in new countries and new industries.
Free software has been a coherent social movement for more than two decades. This movement has produced millions of lines of code, documentation, and a vibrant community of which Simple Invoices is proud to be a part.
Simple Invoices is primarily developed by its users and for its users, in an open process. The goal of the project is to make an invoicing package which is easy to use, easy to adopt and which can reach a community of users that would go far beyond its developers.
As an extension to our focus on community, Simple Invoices is developed for and by the community, anyone is free to help out developing Simple Invoices - writing code, sql, design, graphics, marketing, translating or whatever..