License FAQ

What is the PolyForm license that Crystal uses?

PolyForm is a family of configurable licenses that are intended to be used for software. They are analogous to the configurable Creative Commons (CC) licenses, although the CC licenses aren't intended for software.

PolyForm Noncommercial 1.0.0 is the specific license that Crystal uses. It allows wide noncommercial distribution of the unmodified Crystal program. It does however disallow commercial distribution; you may not sell copies of Crystal nor may you incorporate code from Crystal into works which are themselves sold.

Why is commerical use disallowed?

Crystal's primary author David Foster has spent over 10 years of effort developing Crystal and does not wish that it be sold by others without him receiving any payment.

Why isn't Crystal using an open source license?

Open source licenses, using the OSI definition of "open source", do not allow restricting commercial distribution, making it a poor fit for Crystal. As mentioned above, Crystal's primary author does not wish Crystal to be sold by others without him receiving any payment.