For many developers, open-source software is a passion, a way to contribute to the global coding community. But what if that passion could also be a sustainable revenue stream? A recent case study from the creator of the lightGallery JavaScript library reveals how a dual-licensing model transformed a side project into a significant commercial success, generating over $350,000 in four years.
What Happened
The author of lightGallery, a simple JavaScript library, implemented a commercial open-source software (COSS) strategy centered on dual licensing. This approach involves offering the software under two distinct legal terms:
- A Free, Copyleft Open-Source License: Typically GPL or AGPLv3, which mandates that any derivative work or project incorporating the code also be open-sourced under the same license.
- A Paid, Commercial License: Granting users the right to incorporate the software into proprietary, closed-source projects without triggering the copyleft obligations.
The core of the business model lies in the 'viral' nature of copyleft licenses. When a company, particularly an enterprise, integrates GPL-licensed code into its product or website, it often faces a dilemma: either open-source its entire project to comply with the license or purchase a commercial license. For most businesses, opening their entire codebase is not a viable option, making the commercial license a necessary compliance solution.
Choosing the Right License
For those considering this model, the choice between GPLv3 and AGPLv3 is critical, as it dictates what triggers the open-source requirements:
- GPLv3: Ideal for libraries and frameworks, its open-source requirements are triggered upon distribution. If a developer uses GPLv3-licensed JavaScript on a public website, they must comply by open-sourcing their site or acquiring a commercial license.
- AGPLv3: Best suited for SaaS products, it addresses the “SaaS loophole.” Its requirements are triggered when a user interacts with the software over a network, even if the code isn't directly distributed.
Handling Contributions
Maintaining ownership and the right to re-license contributed code is paramount for dual licensing. The author highlights two primary methods for managing contributions to ensure you can sell code you legally own:
- Contributor License Agreement (CLA): Contributors grant permission for their code to be used and re-licensed, but they retain copyright.
- Copyright Assignment Agreement (CAA): Contributors transfer full copyright ownership of their contributions to the project owner. The author recommends CAA as the safest option for COSS models and mentions tools like CLA Assistant to automate the signing process on GitHub.
Transitioning an Existing Project
For projects moving from a permissive license (e.g., MIT) to a dual-licensing model, a careful transition is necessary. Permission from all existing contributors is required to re-license their work. If permission is denied, those contributions must be removed. The new dual-licensed version should be released as a new major version (e.g., v3.x to v4.0), ensuring older versions remain under their original free licenses and preventing accidental compliance breaches for users of package managers.
License Delivery and Payments
The author utilizes Kelviq (opens in a new tab) for automated license file delivery, key generation, and checkout. Kelviq charges 3.5% per transaction, handling taxes and compliance, and provides a customer portal. (Full disclosure: The author is a co-founder of Kelviq.)
Why It Matters
This success story provides a compelling blueprint for developers and organizations navigating the open-source ecosystem, offering insights into both creating and consuming open-source software:
- For Open-Source Developers: It demonstrates a viable and proven path to monetize projects, allowing creators to dedicate more time and resources to their tools. This can lead to higher quality, better maintained, and more feature-rich open-source libraries, frameworks, and applications. The specifics around license choice (GPL vs. AGPLv3) and contributor agreements are crucial technical and legal considerations for anyone considering this model.
- For Enterprises and IT Teams: Companies using open-source libraries must be acutely aware of licensing terms, especially copyleft licenses like GPL and AGPLv3. Integrating such components into proprietary products without a commercial license can lead to significant legal and compliance headaches, potentially forcing a costly re-architecture or an unwanted open-sourcing of their own IP. This model provides a clear, compliant pathway for commercial use, albeit with an associated cost.
- For the Open-Source Ecosystem: While not without its critics, dual licensing offers a model for the sustainability of open-source projects. It bridges the gap between the free software philosophy and the need for developers to earn a living, potentially increasing the number and quality of maintained open-source projects available to everyone.
What To Watch
As the open-source landscape continues to evolve, the dual-licensing model's prevalence and its impact on the community will be key areas to observe. Developers embarking on similar ventures should pay close attention to:
- Community Acceptance: How will the open-source community respond to increasingly commercial models? Striking a balance between monetization and community ethos will be crucial for long-term project health.
- License Innovations: Will new hybrid licenses emerge that offer different monetization avenues while balancing open-source principles? The interplay between legal frameworks and developer needs is always in flux.
- Platform Evolution: The role of platforms like Kelviq, designed specifically to streamline COSS monetization, will likely expand, offering more robust tools for licensing, payment, and compliance, further professionalizing the open-source business.
- Legal Scrutiny: As dual-licensed projects become more common, expect increased scrutiny on CLAs, CAAs, and the enforcement of copyleft licenses. Understanding the legal nuances will be more important than ever.