Anti-rival good

This term is a neologism, coined to describe goods that are created by a process of reciprocal exchange for mutual benefit, such as open source software.

This case can be clearly from distinguished from public goods, but it does invoke reciprocity and the notion of a gift economy.

The term is explained by Lawrence Lessig:

It's not just that code is non-rival; it's that code in particular, and (at least some) knowledge in general, is, as Weber calls it, 'anti-rival'. I am not only not harmed when you share an anti-rival good: I benefit.

An anti-rival good meets the test of a public good; it is non-excludable (freely available to all) and non-rival (consumption by one individual does not reduce the amount available for others). However it has the additional quality of being created by private individuals for common benefit, but without being motivated by pure altruism.