विपुल!

Copyleft Licenses for Open Core Solutions

⚖️🧑‍⚖️‍📝 for dummies, by a dummy, by not a lawyer

I am not the biggest fan of open core, but it remains a preferred mode business strategies for a few of our cohort companies see who I am and what I do. Open core projects have gained significant popularity in recent years, offering businesses the ability to benefit from the collaborative development of the open source community while also monetizing proprietary add-ons and extensions. Choosing right license is critical when making such decision. Let's see some of copyleft licenses that we can use for such scenario, and if I have a favorite (it's MPL).

The Mozilla Public License (MPL)

The Mozilla Public License (MPL) is a popular choice for open core projects because it strikes a balance between permissive and copyleft licenses. Open core projects typically consist of an open source core product and proprietary add-ons or extensions. The MPL allows for these types of arrangements, making it a good fit for open core. Here's how one can build proprietary software around an MPL-licensed open source solution:

  1. File-level copyleft: Unlike the GNU General Public License (GPL), which applies copyleft restrictions to the entire software, MPL applies copyleft at the file level. This means that any changes made to MPL-licensed files must also be released under MPL. However, this doesn't restrict the licensing of other files in the same project. You can create proprietary extensions or modules that interact with the open source core without having to release them under MPL.

  2. Clear separation: To build proprietary software around an MPL-licensed solution, it's crucial to have a clear separation between the open source and proprietary components. This can be achieved by developing the proprietary components as separate modules, plugins, or extensions that interact with the open source core via well-defined APIs.

  3. License Mixing: You can choose any proprietary license for the additional components, as long as you respect the terms of the MPL for the open source core. Ensure that you comply with the MPL's requirements, such as providing the source code of the MPL-licensed files, documenting modifications, and including appropriate notices and license information.

  4. Distribution: When distributing your software, include the MPL-licensed core components and your proprietary components. You can sell the proprietary components and provide the open source core for free, or offer different pricing tiers based on the features provided by the proprietary components.

While MPL is an attractive option for open core projects, there are other copyleft licenses to consider, each with its own benefits and drawbacks:

GNU Lesser General Public License (LGPL)

A weak copyleft license designed for software libraries, allowing proprietary applications to link to LGPL-licensed libraries without releasing the entire application under LGPL. However, if you modify the LGPL-licensed library, you must release those modifications under LGPL.

Common Development and Distribution License (CDDL)

CDDL is weak copyleft license - file-based like MPL, but has a broader definition of "derived works", and requires that any modifications or derived works be licensed under CDDL. It also mandates that CDDL-licensed software is distributed with the source code, whereas MPL allows for source code distribution upon request. CDDL may have compatibility issues with other licenses, such as GPL, which can limit its adoption in some cases.

Eclipse Public License (EPL)

EPL is similar to MPL in that it applies copyleft provisions at the file level, allowing for proprietary extensions or modules to be built around an EPL-licensed open source core. However, EPL has a "patent retaliation" clause, which states that if a licensee initiates legal proceedings against the licensor for patent infringement, they lose the right to use the EPL-licensed software. This clause is not present in MPL and can be an important consideration for some projects.

Additional resources

I am not a lawyer and the information provided in this blog is not legal advice. This document is not intended to create an attorney-client relationship, nor is it a substitute for legal advice from an attorney licensed in your jurisdiction. The information contained in this document is for general informational purposes only and may not reflect the most current legal developments or laws applicable to your situation.

#foss #legal