Commons Clause
A half-page licence rider that forbids selling the software – and in doing so turns an open licence into something that no longer is one.
Lawyer Heather Meeker drafted it in 2018, with FOSSA founder Kevin Wang among those pushing for it. It sits on top of an existing licence, often Apache 2.0, and removes the right to "sell" the program – where selling explicitly includes offering services whose value derives substantially from it. The target was cloud providers charging for other people's databases as a service.
Redis Labs applied it to some of its modules in August 2018 and got an outcry in return, not least because the result still looked Apache-licensed at a glance. The company switched to a licence of its own the following year. The clause nonetheless fired the starting gun for the wave of source-available licences, and keeps its place in history as the first attempt rather than the most successful one.