New "fair source" movement aims to bridge the gap between open source and proprietary licensing

Open source software isn't profitable enough and "proprietary" has negative associations

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What just happened? A $3 billion startup called Sentry is backing a new licensing model aimed at striking a balance between open-source and proprietary software. Dubbed "fair source," this model seeks to avoid the negative connotations associated with the term "proprietary" while still protecting business interests.

The development was highlighted by TechCrunch, which spoke with multiple proponents and experts on the subject.

Sentry is a software company that specializes in app performance monitoring. Chad Whitacre, Sentry's head of open source, told TC that the motivation behind creating a new licensing model is profitability. He said open source is a "distribution model," not a "business model," making it impractical due to the complexities of various licensing terms.

While there are highly successful open-source projects, they often serve as components within larger proprietary products. Companies that embrace open-source licensing have also frequently reversed course to protect their work, transitioning to more restrictive copyleft licenses or abandoning open-source altogether.

Sentry itself initially offered its product under the permissive BSD open-source license but switched to a more restrictive business source license in 2019 to prevent competitors from "plagiarizing or copying our work," according to co-founder and CTO David Cramer.

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Last year, after mistakenly labeling a newly acquired tool as "open source" despite licensing it under non-OSI-compliant terms, Sentry recognized the need for new terminology to describe its approach.

This led Sentry to formalize the "fair source" label, alongside recommended licenses such as the Functional Source License and Business Source License. Key principles of the model include publicly available source code, allowing third-party use and modification with "minimal restrictions," and a delayed open-source publication clause, where the software transitions to a true open-source license after a predefined period (two years under Sentry's Functional Source License).

The delayed open-source provision aims to protect commercial interests in the short term, while eventually transitioning to an open-source license. In essence, the model allows companies to monetize software in the open without fully committing to open source from the outset.

Beyond Sentry, early adopters of the fair source model include GitButler, founded by a former GitHub leader, as well as CodeCrafters, PowerSync, Ptah.sh, and Keygen, whose founder Zeke Gabrielse is collaborating with Whitacre on fair source governance.

However, the ambiguity around what qualifies as "minimal restrictions" remains an open question as the fair source definition evolves. Whitacre positioned it as a long-term effort, drawing parallels to how the open-source definition solidified over 25 years.

"Some of this is open for conversation; we want to see what emerges and pin it down over time," he told TechCrunch.