What is the best license to apply on an open-source project that I intend to sell commercially as well?

This is about how we chose license for our product. Hope it helps your decision making.

We, Nature Easy Soft, are a group of young people who love open source and we focus on problems within professional enterprise management. ZenTao PMS, Changer and Ranger are three open source product of us, which serve enterprises in different aspects, and the licenses used in the three product are slightly different. ZenTao and Ranger have been released under LGPL, while Changer under ZPL, a license drafted by our team. Now let me share some thoughts of how to choose licenses for open source software with you.

Why chose LGPL to release ZenTao and Ranger? Because LGPL is more moderate, compared to other licenses. GPL, LGPL, AGPL, Apache, BSD and MIT licenses are commonly used licenses. In terms of strictness, AGPL is the most strict one, and Apache, BSD and MIT are relatively not so strict. We did not choose GPL or AGPL, because these two are too strict for some companies that they restrict software released under GPL or AGPL. Consequently, it will affect the promotion of our products. Besides, BSD, Apache and MIT licenses are far too loose that we can barely do nothing, if our code was copied and modified by others to release it as a copycat. This has actually happened to us, and we can not learn from the reproduction. Considering all the pros and cons, we chose LGPL to release our ZenTao and Ranger.

Changer, our Enterprise Marketing tool, was release under LGPL at the beginning, but we chose ZPL over it later. This is due to the special features of Changer which is designed to assist enterprises to build their official website. Changer has a lot of functions and is simple to operate, so it is an perfect option for many website design services and individuals. We were thrilled to know that Changer is so popular, but also frustrated that some users removed our logos. In terms of product promotion, we would like to see that Changer logo and links could be kept, but we also knew that LGPL cannot restrict such removal. On the other hand, Changer is for public and external, and the users are more concerned about license, compared to ZenTao and Ranger users who use our products mainly inside of their organizations. However, they might clearly understand what LGPL is, because it is written in English. Therefore, we drafted Changer License (ZPL) which can be summarized as keep Changer logo and links and you can use Changer freely. Detailed items can be found HERE.

It is frequently asked whether third-party code is accepted. The answer is NO. The main reason is to protect the copy right of the code. For mature open source software, you have to sign related copy right notice before you submit your code to it. However, it is the situation in China that someone would release what they code for work as an open source software, which is illegal. The code is what you created at work and for your work. If not clearly stated, it belongs to your employer. Unless your employer is for open source, you should not release it. Therefore, third-party code is not accepted, but there is something else you can do to release your software with us. You can release your code as plug-ins, and the copy right will be yours. You can release it as open source or paid service, which is pretty flexible and ensure the copy right of the code. It saves much ado for both parties, if there are some big moves, such as donating code to certain foundation. In that case, we do not have to contact each third party to sign the legal documents.

Open source license is more related to the purpose of the author of a software. As a business entity, Naure Easy Soft is more cautious when it comes to choose a license. If you take it more as a hobby, you can choose BSD and the like which is not so strict.