Fair Source
A licensing model in which code is readable and usable from day one, bars competing services for a while, and turns into open source after a few years.
Sentry launched the label in August 2024, having previously used the Business Source License. Its own Functional Source License from 2023 is the template: anything short of building a competing product is allowed, and each release converts automatically to Apache 2.0 or MIT after two years. The idea goes by the name delayed open source publication.
Fair Source is, at heart, source-available with better branding and an expiry date. The point of the name is to avoid calling it open source — which the OSI wouldn't have accepted anyway — without sounding like the SSPL crowd who closed their projects in a fit of pique at the cloud providers. Whether a two-year head start is a business model remains to be seen.