Questions and answers on donations
Developing and maintaining SWI-Prolog has become a full-time job. Some of this work can be done in University projects, but only as far as this is beneficial to these projects. The rest is spare time.
We are firm believers in the Open Source and Free Software philosophy, producing high-quality software in a very cost-effective way. Free Software has many advantages for you. You can inspect it, modify it, re-assemble it with other free software, distribute it and be pretty sure it will not simply disappear due to financial or legal `events'.
The ideal would be if every user pays a small fee for downloading the system. If there existed a good mechanism for this which is as easy as using your phone it would be great. As low as 0.5 USD per download would make it work, an amount even most students won't find a big problem. Unfortunately there are only clumsy, insecure or both alternatives at the moment.
We would like to arrive at a situation where the main developer can spent near fulltime on the development and we are able to financially support important projects to make them happen, such as reorganising the documentation.
For the development and maintenance of SWI-Prolog. The SWI-Prolog foundation is a very small organisation with little overhead. A foundation is legally restricted to use its financial resources exclusively to supports its goals. The University appreciates the publicity and technical know-how the project brings to it.
SWI-Prolog will always be free. Of course you may not trust our words, but the LGPL cannot legally be `undone'. We can in theory change the license of the parts we own but we cannot deny you the rights we have already given you. As more people contribute to the system and therefore `own' part of the system license modifications quickly get impossible.
We are not planning to give up easily as any alternative implies restrictions of some kind. Paid support, paid add-ons and paid access to the most recent versions come to mind. This means more hassle for you and us.
Access to hardware running an up-to-date operating system can help to make SWI-Prolog run better on some platform: fit in with native package format, tuning of compiler settings for optimal performance, quickly fix problems, etc. Remote access to a well maintained machine is sometimes more valuable than a locally installed machine.
We have two payment handlers. Kagi is more suitable for organisations as does not require registration, can handle many methods of payment at the price of a much higher fee.
With PayPal you attach an account to your E-mail address and optionally to your creditcard or bank account. This requires you to become a member of paypal. After this signup, which takes a few minutes, you can send and receive money at very modest rates.
Kagi is a more traditional payment handling firm. You do not become a member and it can handle creditcards, checks and even cash. Unfortunately its fees are high, making 20$ about the bare minimum:
?- Fee is min(0.05*Amount+5, 0.10*Amount+2.5).
Any amount is welcome. The table below gives some guidelines. Probably it sounds like a lot of money for `free'. `Free Software' however first of all means freedom to use it as you please. Compare a donation to what you would pay for a commercial system and compare what you get. We will update this table based on experience and your feedback.
| User profile | Suggested amount (USD) |
|---|---|
| Student | 5 |
| Academic, course | 500 |
| Academic, research | 500 |
| Private | 30 |
| Corporate, 1 developer | 250 |
| Corporate, 2-5 developer | 500 |
| Corporate, large | Consider special arrangement |
Please contact us and we will send you one. Indicate how much you want to donate as well as other details on the desired invoice.
You get an E-mail from PayPal confirming you have made a donation to the SWI-Prolog foundation as well as a credit-card notice with the same information. If this does not suffice for you, please contact us.
Maybe you would like to pay, but you like none of the provided options, they are impractical or impossible for you. We can arrange alternatives for you or adjust these pages. Please contact us.
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