If the library is licensed under LGPL (Lesser General Public License) You\'re fr
ID: 659938 • Letter: I
Question
If the library is licensed under LGPL (Lesser General Public License)
You're free to use the library however you want as long as you don't modify it or create any derived works from it.
Whether a work that uses an LGPL program is a derivative work or not is a legal issue. A standalone executable that dynamically links to a library is generally accepted as not being a derivative work (in LGPL). It would be considered a "work that uses the library" and paragraph 5 of the LGPL applies.
Here's Paragraph 5:
A program that contains no derivative of any portion of the Library, but is designed to work with the Library by being compiled or linked with it, is called a "work that uses the Library". Such a work, in isolation, is not a derivative work of the Library, and therefore falls outside the scope of this License.
That means, don't modify and compile the source. Just use the dll that the site provides and you can use it on whatever you want (even proprietary software).
Most open source libraries should be covered by this license (unless they're authored by a GPL nazi).
The MIT License is the other licence you may encounter a lot
MIT is significantly more liberal than the GPL (General Public License) or even the LGPL (Lesser General Public License).
It's so simple I can quote the whole thing directly here:
Copyright (C) by
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
Basically, you can do what ever the hell you want with it for free (including modify and sell it) as long as you maintain the rights that anybody can do whatever the hell they want with it for free.
When I write open source software I prefer this license because it doesn't contain the 'viral' traits and (IMHO) legal sleaziness that GPL does. If I'm going to go to the effort to make it free, I might as well make it truly free.
Note: With GPL if you use it, not only do you also have to license your project under GPL but you have to share the source of any changes you made to the source. I don't see much freedom in that.
Explanation / Answer
There are many licenses that would fit this, see the licenses under "Release changes under a different license" here: Comparison of free software licences
You didn't say that you intend to keep your own software closed source (people do sell open source software), but I assume that's what you meant or you probably wouldn't have asked the question.
Practically all open source software that is distributed as a library (i.e. you don't have to recompile their code to use it, just link to it) has a license that permits your intended use, but you should give it a once over or post the details here when you select a specific one, because there are exceptions, mysql being perhaps the most notable. If you are also distributing the library, not just instructing your users to download it from the original site, you usually also need to provide a link to download the library's source, even if you don't have to open your own source. Also, there may be attribution requirements to keep in mind.