License To Code
It can be tricky to know what you can and can’t use when looking at free libraries. The following is a quick rule of thumb for Open Source Licenses.
Good
Bad
Some licenses are explicitly not OK to use. For example, none of the copyleft licenses can be used in a closed source project. The following list is not exhaustive. Just because a license is not on the list does not automatically mean that it can be used.
Dual Licenses
It is possible for a project to have more than one license specified. Unless specified otherwise in their licensing, all clauses from all licenses may apply. This means that, to be safe, each license to be on the compatible with the consuming project.
Other Licenses
Any other license must be evaluated on a case by case basis.
More Information
The Open Source Initiative has lots of useful information about OSS licensing. Choose A License does a great job of breaking down the most common licenses comparing the differences between them.