Not open source. Not closed source. The Fair Source License allows everyone to see the source code and makes the software free to use for a limited number of users in your organization. It offers some of the benefits of open source while preserving the ability to charge for the software.
See https://fair.io for more information.
How Fair Source Works
The Fair Source License is a license that can be applied to software applications and their source code (in the same way as an open-source license, by adding a LICENSE file). It is not currently suitable for library or plugin code.
Any individual user can view, download, execute, and modify Fair Source-licensed code free of charge. Up to a certain number of users from an organization can use the code for free, too. After an organization hits that user limit, it will start paying a licensing fee determined by the software publisher.
Example: Alice releases FooApp as Fair Source 25, licensed under the Fair Source License with a user limit of 25. Bob can view and modify the code and run FooApp free of charge for personal use. Up to 25 people at Bob’s company can use the code and run FooApp free of charge for business purposes. When 26 or more people at Bob’s company are using or running the code, Bob’s company must pay Alice.