Question:

Could you clarify whether Cygwin is licensed for commercial application without incurring any fees?

Answer:

Cygwin is distributed under the GNU General Public License (GPL) with some components available under the Lesser GPL (LGPL) and others under an X11 style license. This means that most tools within Cygwin are open-source and free to use, even in a commercial setting.

Special Linking Exception:

A notable aspect of Cygwin’s license is the special linking exception. This allows proprietary software to link against the Cygwin library without the entire application becoming subject to the GPL. It means that you can use Cygwin as part of a commercial application without having to release your proprietary code under the GPL.

No Cost for Commercial Use:

There is no fee associated with using Cygwin for commercial purposes. The software is publicly available and free to download, and this extends to commercial applications as well.

Compliance with LGPL:

If you distribute binaries that were built using Cygwin, you must also provide access to the source code in compliance with the LGPL. This ensures that while you can use Cygwin for free in commercial products, you must adhere to the open-source licensing terms when it comes to distribution.

In summary, Cygwin can indeed be used for commercial applications without incurring any fees, provided that you comply with the terms of the GPL and LGPL, particularly regarding the distribution of source code when distributing binaries. This makes Cygwin a cost-effective solution for bringing Unix capabilities to Windows-based commercial environments..