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Frequently Answered Questions

Here are answers to questions we are frequently asked. If you have a question not addressed here, please email us at osi {_AT_} opensource.org.

Can Open Source software be used for commercial purposes?

Absolutely. All Open Source software can be used for commercial purpose; the Open Source Definition guarantees this. You can even sell Open Source software.

However, note that commercial is not the same as proprietary. If you receive software under an Open Source license, you can always use that software for commercial purposes, but that doesn't always mean you can place further restrictions on people who receive the software from you. In particular, so-called copyleft-style Open Source licenses require that when you distribute the software, you do so under the same license you received it under.

Can I restrict how people use an Open Source licensed program?
No. The freedom to use the program for any purpose is part of the Open Source Definition. Open source licenses do not discriminate against fields of endeavor. Note that nearly all Open Source licenses also state that there is no warranty: you can't sue if it blows up your computer or destroys your data, even if it was program's fault. (Some companies may sell you a warranty separately, for a fee, but that is not part of the open source license, it's just your private contract with that company.)
Can I stop "evil people" from using my program?
No. The Open Source Definition specifies that Open Source licenses may not discriminate against persons or groups. Giving everyone freedom means giving evil people freedom, too. Fortunately, there are other laws that constrain the behavior of evil people.
What is "copyleft"? Is it the same as "open source"?

"Copyleft" refers to licenses that allow derivative works but require them to use the same license as the original work. For example, if you write some software and release it under the GNU General Public License (a widely-used copyleft license), and then someone else modifies that software and distributes their modified version, the modified version must be licensed under the GNU GPL too — including any new code written specifically to go into the modified version. Both the original and the new work are Open Source; the copyleft license simply ensures that property is perpetuated to all downstream derivatives.

Not all Open Source licenses are copyleft. When an Open Source license is not copyleft, that means software released under that license can be used as part of programs distributed under other licenses, including proprietary (non-open-source) licenses. For example, the BSD license is a non-copyleft Open Source license. Such licenses are usually called either "non-copyleft" or "permissive" open source licenses

Copyleft provisions apply only to actual derivatives, that is, cases where an existing copylefted work was modified. Merely distributing a copyleft work alongside a non-copyleft work does not cause the latter to fall under the copyleft terms.

For more information, look at the text of the specific copyleft license you're thinking of using, or see the Wikipedia entry on copyleft.

What is a "permissive" Open Source license?
A "permissive" license is simply a non-copyleft license. See the copyleft entry for more information.
Is <SOME PROGRAM> Open Source?
Only if it uses one of the approved licenses, and releases appropriate software.
Can I call my program "Open Source" even if I don't use an approved license?
Please don't do that. If you call it "Open Source" without using an approved license, you will confuse people. This is not merely a theoretical concern — we have seen this confusion happen in the past, and it's part of the reason we have a formal license approval process.
Is <SOME LICENSE> an Open Source license, even if it is not listed on your web site?
In general, no. We run all licenses through an approval process to provide an accepted standard on which licenses are Open Source, and we list the approved ones. Be dubious of claimed Open Source-ness for licenses that haven't gone through the process.
Is <SOME PHP PROGRAM> Open Source simply because it's written in PHP?
No. PHP itself is Open Source, but that doesn't turn all code written in PHP into Open Source. The code written in PHP needs to be licensed under an approved Open Source license in order to be Open Source.
Can I write proprietary code that links to a shared library that's open source?
Sometimes you can; it depends on the Open Source license. Authors often want you to be able to do this, so most shared libraries are licensed under a permissive license or one that allows linking under certain circumstances (e.g., the LGPL). A very small number of libraries use the GPL, which only allows linking with proprietary works if the licensor grants an explicit exception. Thus, you are wise to check the licenses that your program links to. The community expects that all code linked to GPL code will be licensed under the GPL, even if the link is made at runtime using a shared library.
I want to publish some code as Open Source code — can I get a license from you?
As long as you own that source code, all that you need to do is choose one of the approved Open Source licenses, include a copy of the license text, typically in a filenamed "COPYRIGHT", including a statement saying that you are licensing the code under that copyright, and give it to somebody else! Of course, you probably want to give it to a lot of people in order to gain the maximum benefit from giving away your code. A number of websites will help you do that: berlios.de, sourceforge.net, code.google.com, and others.
What if I do not want to distribute my program in source code form? Or what if I don't want to distribute it in either source or binary form?

If you don't distribute source code, then what you are distributing cannot meaningfully be called "Open Source". And if you don't distribute at all, then by definition you're not distributing source code, so you're not distributing anything Open Source.

Think of it this way: Open Source licenses are always applied to the source code — so if you're not distributing the source, then you're not distributing the thing to which an Open Source license applies. You might or might not distribute binaries; that's a separate question. But while some Open Source licenses allow you to distribute binary code without distributing the corresponding source, it is only the source code that can be "open source". The binaries alone cannot be Open Source, because you're not making any source code available to be open. (If someone else distributes the source code under an Open Source license, then that's still Open Source, of course.)

Note that copyleft Open Source licenses require redistributors to make source code available under certain circumstances; for example, see the GNU General Public License and GNU Affero General Public License.

Someone is violating a copyleft license, for example by refusing to give me source code when they are required to. What can I do?

The Open Source Initiative is not a legal services organization and generally cannot help you when someone is violating a copyleft license. However, as of late 2011, one of the organizations below may be able to help (note that most of the enforcement they do is about the GNU GPL and AGPL licenses, though in theory they can help enforce other copyleft licenses too):

If you know of other organizations that provide similar legal assistance, please let us know at osi {_AT_} opensource.org.

Can I use one of your pages in a document I'm writing?
Generally, yes. Look at the bottom of each page for the Creative Commons Attribution 2.5 License. That gives you fairly broad permission to re-use the material; read the license to see the exact permissions.
Can I link to your site?
Yes, but you don't have to ask permission. It's always okay to link to anybody's site. Linking to something is like saying its name and address out loud.
Can I sell Open Source programs? Even if I haven't written it?
Yes, you can. But depending on the license, you probably can't stop your customers from selling it in the same manner as you. See the commercial use for more details.
How do I make money if anybody can sell my code?
You can sell services based on the code (i.e., sell your time), sell warranties and other assurances, sell customization and maintenance work, license the trademark, etc. The only kind of profit strategy that is incompatible with Open Source is monopoly-based sales, also known as "royalties". See this article for how to think about business strategies that make money from Open Source.
How much does it cost for a link on opensource.org to my website?
We don't sell advertising space on our website.
Why did you approve Microsoft's licenses when they are attacking Open Source?
Because those licenses are still Open Source licenses, and people who receive software under those licenses are receiving all the freedoms promised by the Open Source Definition. In general, just because we approve licenses from a given organization does not mean we endorse every other activity that organization engages in, whether it's Microsoft or anyone else.
Can you help me find an Open Source programmer or program?
Unfortunately, we can't; Open Source is now too big for us to keep track of all the people and activities in it. A web search engine is your best bet. For specific software packages, you may also find it useful to look in Freecode.
How do I unsubscribe from one of your mailing lists?
Visit the lists page, and click on the appropriate "unsubscribe" link to generate the necessary email request.
How can I join an open source project?
Most open source projects are run via online discussion forums: mailing lists, wikis, chat rooms, etc. We encourage you to find a project you care about, look at their web site to see what kinds of discussion forums they're using, and join those forums. The usual next step is to starting filing bug reports and/or fixing bugs.
I have a thesis and I'm sending out a survey...
We do not personally answer surveys. Read this for more information.
Can I use your corporate logo (green open keyhole saying "Open Source") or something very similar (different color / texture / words) on my product (hat, shirt, web page, etc)?
Alas, no, it is a trademark and we need to retain control over it.
Can I use your corporate logo on my web page to link to you?
Yes. You can always use a trademark in a truthful manner to refer accurately to an entity.