What license can I choose, if my utility uses another one with a custom license

Question

I recently open sourced a utility which uses PDFtoPrinter.exe. Now I am confused with choosing a license because its homepage says:

This system uses the free PDF-Xchange Viewer. You should consult the linked page to determine whether or not you may use that program for your own purposes. The compiled AutoIt script that wraps the PDF software is free for use by anyone, anywhere, for any purposes whatever.

I have found this "PDF-XChange® PDF Viewer" license here but I am completely confused what licenses my open source project can have now. Should I use the same license or it's possible to find something that will allow me to distribute it with my project?

Answer 1

While I suggest looking at @bart-van-ingen-schenau's answer, I think the simpler (and more correct) answer is that you cannot use PDF-XChange as part of your open source project. The restriction that potential users would have to contact [email protected] for permission, no matter how generous in it's granting, would seem to violate the first tenet of Open Source software:

1. Free Redistribution The license shall not restrict any party from selling or giving away the software as a component of an aggregate software distribution containing programs from several different sources. The license shall not require a royalty or other fee for such sale.

Note that this is generally a problem both for copyleft licenses and more permissive licenses.

Answer 2

The PDF-Xchange software is free of cost, but it is not free in terms of freedom. The relevant portion of the license is (emphasis theirs)

You may use the Free version without charge provided you are the End User and do not intend to distribute or incorporate it with or into any other product or software package intended for resale or distribution for any purpose whatsoever other than as provided for in this license. Should you wish to distribute the PDF-XChange Viewer/Editor (free version) for any purpose, whether for commercial gain or not – please email Tracker at [email protected] and provided you receive no direct commercial or financial gain directly from doing so from such distribution – such permission will usually be granted ‘free’ - promptly.

In layman's terms, this says that you must ask explicit permission to incorporate even the (cost-)free version of PDF-Xchange Viewer in your own project. This in itself does not affect the license of your code, but the terms under which Tracker allows re-distribution of their software and how you integrated the PDFtoPrinter software in your application might affect your licensing options.

As the copyleft licenses, like the GPL, have the strong implication that all parts of the system can be freely re-distributed, also for financial gain, those licenses might not be compatible with the distribution terms of the PDF-Xchange software, but that can only be determined with any level of certainty when those terms are known.

Permissive licenses, like the MIT license, have that expectation to a far lesser extent.

Answer 3

I recently open sourced a utility which uses PDFtoPrinter.exe.

Improve your utility to easily make that PDFtoPrinter configurable (if your utility is a command-line one, add some option like --printer-command=). For example, on Linux, that command is usually lp or lpr (using CUPS). That printer command could even be a .bat script (itself running PDFtoPrinter and also doing some logging) provided by your user.

Then some user might rewrite on his own (perhaps even as an open source program) a functional equivalent of PDFtoPrinter and does not even use that proprietary software. And perhaps some more or less equivalent to PDFtoPrinter, but open source, programs already exist for your operating system.

Other users could play with their PATH variable and symbolic links to use their own variant of PDFtoPrinter

By enabling your user to easily change that particular PDFtoPrinter command used by your open source program, you weaken the relation between your program and that proprietary utility (and in front of a legal court - should you have to legally defend your rights and license -, that would matter a lot).

BTW, in the Unix world, a2ps is a free software program (GPLv3+) conceptually similar to yours.

PS. Your situation illustrates why I prefer most Linux distributions to even free as in beer operating systems (including a Windows sold with a laptop). I actually never used Windows (but Linux since 1993) on my PCs (both at home and at work). I am a computer scientist aged 60.