LGPL Explained

LGPL Explained

LGPL. The GNU project has two main licenses for use in libraries. One is the GNU Lesser GPL (or LGPL see abbreviationfinder.org) or reduced GPL, the other is the ordinary GNU GPL. The choice of one or the other license is very important: using the LGPL allows the use of the library in proprietary programs. Using the ordinary GPL for a library makes it available only for free programs.


Which license is the best for a certain library is a matter of strategy, and depends on the specifics of the situation. Currently, most GNU libraries are covered by the LGPL, and that means that they are using only one of these two strategies, neglecting the other. So now they want more libraries to be released under the ordinary GPL.

Proprietary software developers have the money advantage, free software developers need to favor each other. Using the ordinary GPL for a library gives free software developers an advantage over proprietary developers: a library that they can use, while proprietary developers cannot.

Using the ordinary GPL is not advantageous for all libraries. There are reasons that may make the use of the LGPL more appropriate in certain cases. The most common case is when the free library features are already available to proprietary software through alternative libraries. In that case, the library cannot give free software any particular advantage, so it is better to use the LGPL for that library.

While the GPL license offers great benefits, there are times when it offers certain restrictions. An example is that a software that uses a GPL component must be licensed under it, that is, parts or GPL software libraries cannot be used in proprietary software or distributed under another license.

These restrictions bring some problems. For example, if a commercial company wants to use only a small GPL library within its software, it would be obliged to distribute all its software under the GPL, which it may not decide to do and for some cases such as general-purpose libraries this also does not help the improvement of the library itself since it would not be chosen for example to become a standard. That is why the LGPL license appeared, at first called Library GPL in reference to that it was especially used for libraries, but then it became popular and began to be used even in many complete programs due to its commercial benefits (it allows it to be used together with non-free software) and changed its name to Lesser GPL, which means less restrictive GPL.

However, when a library provides unique functionality and important, as Readline of GNU, that’s another matter. The Readline libraryimplements editing and input history for interactive programs, and that’s a feature generally not available elsewhere. Releasing it under the GPL and limiting its use to free programs gives the community an important boost. There is at least one application that is free software today specifically because that was a necessary requirement to be able to use Readline.

If we accumulate a collection of powerful GPL-protected libraries that have no equivalent in proprietary software, we will have a set of useful modules that will serve as building blocks in new free programs. This will be an important advantage for the further development of free software, and some projects will make the decision to make free software in order to use these libraries. College projects can be easily swayed; Today, as companies begin to consider making free software, even some commercial projects can be influenced in this way.

Developers of proprietary software, trying to deprive free competition of an important advantage, will try to convince authors not to collaborate with libraries to the whole protected by the GPL. For example, they might tempt us with self-esteem, promising “more users for this library” if we let them use the code in proprietary software products. Popularity is tempting, and it is easy for a library programmer to get the idea that what the community needs above all is to boost the popularity of that library.

But we should not listen to these temptations, because we can achieve much more if we stick together. We free software developers must support each other. By publishing libraries that are limited to free software only, we can help other people’s free software packages win out over proprietary alternatives. The entire free software movement will become more popular, because free software as a whole will be valued better against the competition.

Another current example is OpenOffice.org, since from Beta version 3, it changed its license this time to version 3 of the GNU Lesser General Public License (LGPL v3). Sun is changing the license for the OpenOffice.org codebase to the more flexible and protective LGPL v3, according to its official announcement. The LGPL v3 adds to the terms of the original GPL 3.0, published in June of last year, terms that allow closed source programs to reference other LGPL code at runtime, such as assignment libraries. dynamic.

Notes on the translation:

The term library has been translated in this text as “library”, instead of its correct translation “library” as this first denomination is more in accordance with the computer terms used in Spanish.

The main objective of this translation is to explain the LGPL license, however said translation must be very “literal” on several occasions so as not to fall into personal interpretations.

This is an unofficial translation of the GNU Lesser General Public License into Spanish. It was not published by the Free Software Foundation, and does not legally state the distribution terms for software that uses the GNU LGPL – only the original English text of the GNU LGPL does that. However, we hope that this translation will help Spanish speakers understand the GNU GPL better.

This is an unofficial translation of the GNU Lesser General Public License. It was not published by the Free Software Foundation, and it does not legally set out the terms of distribution of software used by the GNU LGPL; only the original English text of the GNU LGPL does. However, we hope that this translation will help Spanish speakers to understand the GNU LGPL better.