With the Functional Source License, Sentry wants to give developers freedom ‘without damaging free riding’

Yet another software license is competing for the attentions of SaaS companies seeking to adapt themselves to the open source realm, without compromising their commercial efforts.

watchedan app performance monitoring (APM) company that helps companies like Disney, Microsoft, and Cisco track and resolve laggy or buggy applications, has shifted its main product to a new license it designed called the Functional Source License (FSL). The company’s head of open source Chad Whitacre says the license is for any SaaS company that wants to “give freedom a harmless free ride.”

“There’s a long history of companies with deeper pockets and more resources taking advantage of traditional open source companies,” Whitacre told TechCrunch via email. “Open source companies, regardless of the license or the pedantic definition, are increasingly dependent on being business-backed, for-profit, or more importantly supported by companies that trust their code.”

moving On

Recent history is filled with examples of companies that grew up behind open source projects, but later abandoned the roots to protect their commercial interests. In 2021 Elastically transferred Elasticsearch went from an Apache 2.0 license to a duo of source-available licenses, a move designed to prevent third-parties like AWS from essentially selling their own version of Elasticsearch “as-a-service” without contributing to the original project. More recently, HashiCorp has done something similar with Terraform, while the likes of Element (with Matrix) and Grafana transferred from permissive open source licenses to so-called “copyleft” licenses, essentially forcing users to keep derivative projects open source, or pay for a license to use the product.

As for Sentry, the San Francisco-based company started more than a decade ago under a permissive BSD 3-Clause license, one with less restriction. Like the other aforementioned companies, Sentry relicenses its core product back in 2019 to counter what co-founder and CTO David Cramer calls “funded businesses that copy or replicate our work to compete directly with Sentry.

“This includes taking marketing content from our website, plagiarizing our documentation and framing it as their own, or directly copy/pasting our product visuals,” Cramer wrote at the time. “Their defense? ‘Well, it’s free open-source, and we can do that.’ These businesses aren’t using Sentry to improve how they build software; they removed its code and assets to build their closed-source products to compete directly with us.

Therefore, Sentry has switched to the Business Source License (BSL), a source license that allows unlimited use in most non-commercial scenarios. In particular, BSL-licensed products are time-limited, automatically reverting to an Apache open source license after four years – this is designed to prevent commercial competitors from benefiting from a project in short term. However, Whitacre argued that four years was too long, and inconsistent with the spirit of open source.

“The default non-compete period is four years, which is a long time in the software world,” Whitacre wrote. in a blog post on Friday. “It can feel like the last Open Source change was just a token effort. It’s also been almost 100 years.”

While Sentry actually shortened the BSL license to three years, Whitacre says that’s too long. In addition, the BSL license contains other errors, such as “additional use grant” mechanism, which allows project owners to define specific circumstances under which their code can be used commercially

“The increased use grant is the biggest problem,” Whitacre wrote. “It’s a giant fill-in-the-blank that effectively means every BSL is a different licence.”

This variability means that BSL-licensed products are often difficult to get approved from companies’ compliance departments, as they must review each license individually.

“It also makes it difficult for companies to adopt BSL for their own products, because they have to make decisions and write custom language for it,” continued Whitacre. “We want to widely promote the values ​​that brought us to BSL, and to that end we want to heal the friction, in FSL.”

Sentry calls FSL the “evolution of BSL” that balances user freedom and developer continuity. There is no additional grant to use the area, plus the time limit is cut to two years, after which the associated products will automatically be transferred to an Apache 2.0 or MIT license.

“For companies using FSL, two years provides protection against competition, but also acts as an incentive to continue to innovate,” Whitacre wrote. “For the user community, two years provides meaningful protection once the driving company drops the ball.”

However, Thierry Carrezgeneral manager of Open Infrastructure Foundation and vice chair of the Open Source Initiative (OSI) in charge of DEFINITIONS of open source software, says Sentry is just the latest in a line of companies that built their reputation on the back of open source and then “abandon the model that made them successful in the first place.”

“Releasing yet another license variant that removes developers’ own sovereignty over their technical choices is not something new – it’s about removing important freedoms from the entire software ecosystem to clearly state the ownership of their proprietary software and the use you are allowed to make of it,” Carrez said. “It’s not open source: it’s proprietary gatekeeping wrapped in open laundered clothing.”

Leave a comment