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Can I create commercial software using SageMath?

asked 2016-08-11 22:05:55 -0500

dsejas gravatar image

Dear SageMath Community, suppose I am hired to develop a piece of software that solves differential equations, and I use SageMath to make the programming. Since SageMath is GPL'ed, should my software be GPL'ed too? This question is more of a technicality: I understand (some of) the GPL terms, but there is also the following situation: A programming language that is GPL'ed can be used to create executables that can be commercial. For example, if Python was GPL'ed, I could create a program to solve differential equations, and still sell my Python software (my code), but if I were to create a new language by making modifications to Python, the new language should be GPL'ed.

In that case, considering SageMath as a programming language, can I write commercial software that uses SageMath to solve a problem?

Thanks in advanced for your answers!!!

Diego Sejas

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Are you planning to sell some service based on software that uses Sage, or to sell software that includes Sage?

slelievre gravatar imageslelievre ( 2016-08-16 19:44:43 -0500 )edit

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answered 2016-08-16 23:57:10 -0500

William Stein gravatar image

updated 2016-08-16 23:58:30 -0500

ANSWER: It depends on what you mean by "commercial software".

  • ONE: If by "commercial software" you mean "closed source", then the answer is no, you can't write and publicly distribute such software legally.

If you write a program that genuinely uses the Sage library in a nontrivial way, then that program is a derived work of Sage and must be distributed under the GPL (after all, there is no possible way to run the program without calling many functions in Sage).

When I started Sage, I took PARI -- a GPL'd program -- and started building Sage on top of that. I was forced to GPL Sage because it was a derived work of PARI. It's the same principle at work. Sage is very much a LIBRARY, not just a programming language.

We (Sage developers) also cannot sell or provide you with an exception, because Sage itself depends on many GPL'd programs that we do not own the copyright to.

  • TWO: If by "commercial software" you mean software that makes money", then yes, it is possible to build commercial software on top of GPL'd software such as Sage. E.g., SageMathCloud is commercial (it makes money) but is GPL'd. The Linux operating system is also GPL'd but there are companies (like RedHat and Ubuntu) that make money from that software.
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Dear William, thank you very much for your answer; it helped me a lot.

I would like to use this opportunity to thank you for your efforts to make such a great software as SageMath available to us. I really hope you succeed in your endeavor.

Diego Sejas.
dsejas gravatar imagedsejas ( 2016-08-17 19:02:46 -0500 )edit

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Asked: 2016-08-11 22:05:55 -0500

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Last updated: Aug 16 '16

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