> /v1/glossary/fair-source · LICENSE-MODEL
Fair-Source
A category of source-available licenses that auto-convert to open source after a delay — most prominently the FSL.
Fair-source is a label coined by Sentry in 2024 to describe a category of licenses that publish source code with delayed open source conversion. The Functional Source License (FSL) is the canonical example: code is source-available with non-compete restrictions for 2 years, then automatically converts to Apache 2.0 or MIT.
Fair-source aims to give companies the commercial protection they need without permanently restricting the code. After the delay period, the code is fully open source by any definition.
Adopters: Sentry (FSL), Keygen, Anyscale, and a growing list of "intent-to-be-open" startups.
Critics argue fair-source dilutes the meaning of "open source" by association, since the marketing emphasizes the eventual open conversion while users today operate under restrictions.
// EXAMPLES
// RELATED TERMS