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Open-Source Licenses

Dive into open-source licenses: types, benefits, and selection considerations. Learn their role in forming a robust SBOM. Master modern software practices.


The open-source movement has profoundly shaped the software development landscape, fostering innovation, collaboration, and transparency.

Open-source software (OSS) is freely accessible and usually comes with a license that dictates how the software can be used, modified, and distributed.

These permissions and restrictions form an integral part of an application's Software Bill of Materials (SBOM), a comprehensive record of the components that make up a software system.

Understanding open-source licenses is not just a technical necessity—it's a strategic imperative for engineering teams and their leaders.

As OSS permeates more aspects of technology, understanding its legal framework becomes crucial to mitigate risks, protect intellectual property, and ensure software sustainability.

This article provides an overview of open-source licenses, highlighting their types, key factors to consider when choosing a license, and the benefits of adopting them.

Let's delve into this essential aspect of modern software development.


What is an open-source license?

An open-source license is a legal agreement that governs the use, modification, and distribution of open-source software. It grants users the freedom to study, change, and improve the software, with the source code being publicly accessible.

Open-source licenses are integral to the ethos of the open-source software movement, facilitating the free exchange of ideas and collaborative development.

They allow the software to be freely used, copied, studied, and changed while also providing provisions to ensure the original authors' credit is maintained.

While there are different types of open-source licenses, each with its own terms and conditions, they all promote the fundamental principle of open-source software that knowledge should be shared openly and freely.

Therefore, understanding an open-source license is crucial for anyone involved in developing, contributing to, or using open-source software.


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Types of open-source licenses

Before diving into the specifics of different open-source licenses, it's crucial to understand that not all open-source licenses are created equal.

They come with varying terms and conditions that can significantly impact how the software can be used, modified, and distributed.

These terms can influence the overall sustainability of the project, the integration with other software, and the legal safety of users and contributors.

Now, let's take a closer look at the different types of open-source licenses: Permissive and Copyleft licenses.

📚 Related: Open Source Initiative®️

1. Permissive licenses

Permissive licenses, also known as "anything goes" licenses, are known for the broad rights they offer.

They allow users to use, copy, modify, merge, publish, distribute, sublicense and even sell copies of the software. The primary condition is that the original copyright notice and disclaimer must be preserved.

  • The MIT license
    One of the most popular permissive licenses is the MIT license. Its simplicity and brevity have made it a preferred choice among developers. It allows for maximum freedom while minimizing legal liability. This flexibility makes it an ideal choice for businesses interested in incorporating open-source software into proprietary software.
  • The Apache license
    Another widely adopted permissive license is the Apache License. In addition to the terms of the MIT License, the Apache License also provides an express grant of patent rights from contributors to users. This feature offers additional legal protection against patent claims.
  • BSD Licenses
    This includes the original "BSD License" and its two derivatives - the "New BSD License/Revised BSD License", and the "Simplified BSD License/FreeBSD License". All are very permissive, differing mainly in the number of clauses in the license.
  • ISC License
    Functionally equivalent to the simplified BSD and MIT licenses, the ISC license has been used for many of the most important and influential open-source projects of the last 30 years.
  • Zlib License
    This is a very permissive, free software license that is compatible with the GPL and often used for graphics libraries.

2. Copyleft licenses

Copyleft licenses, or "viral" licenses, come with a crucial stipulation: if you modify the open-source software and distribute the modified version, you must also distribute the source code of your modifications under the same license.

Here are the most common Copyleft licenses ordered by restrictiveness:

  • GNU Affero General Public License (AGPL)
    The AGPL is considered the most restrictive copyleft license. It's similar to the GNU GPL but has an additional provision concerning software run over a network. If you use AGPL-licensed code in your web service, you must provide the entire source code to the users of that service.
  • The GNU General Public License (GPL)
    The GPL is the most well-known copyleft license. The "share-alike" principle ensures that improvements flow back to the community. This license is best suited to projects where the intention is to encourage an open and collaborative community.
  • GNU Lesser General Public License (LGPL)
    LGPL allows software libraries to be linked to software that may be distributed under a different license. It's less restrictive than the GPL and AGPL.
  • Eclipse Public License (EPL)
    The EPL falls into a category known as a "weak copyleft" license. It allows for more flexibility in integrating with proprietary software, making it a popular choice for commercial software developers.
  • Mozilla Public License (MPL)
    The MPL is another "weak copyleft" license. It allows you to combine the MPL-licensed code with proprietary code, as long as you keep the MPL-licensed code in separate files.



Key factors to consider when choosing an open-source license

1. License compatibility

One of the primary factors to consider when choosing an open-source license is license compatibility. This refers to the ability to use, modify, or distribute code under the terms of another license. I.e. when you want to integrate code from one project with a different license into your project.

With complex software dependencies, ensuring licenses are compatible across dependencies is crucial to avoid legal issues and to promote seamless software integration.

Not all licenses are compatible, as they may contain conflicting requirements. For example, a GPL-licensed project cannot include code from an Apache-licensed project, because the GPL's requirement for a full copy of the license text in every file conflicts with the Apache license's more relaxed terms.

For a better understanding of how different software components interact with each other, organizations often turn to a Software Bill of Materials (SBOM).

An SBOM is a detailed inventory of all software components within a product, including their open-source licenses. This document can help businesses identify potential licensing conflicts and manage them proactively.

2. Restrictions and requirements

Each license comes with its own set of restrictions and requirements. For instance, the MIT License requires the inclusion of the original copyright notice and license text in all substantial copies of the software.

The GPL, on the other hand, requires that derivative works must also be GPL-licensed. It is crucial to understand these restrictions and choose a license that aligns with the goals of your project.

3. Legal and intellectual property protection

Every open-source license offers some level of legal protection. They define the terms of use, distribution, modification, and contribution, which, if breached, can lead to legal consequences.

They also provide intellectual property protection, offering a safeguard against direct copying and marketing of your open-source software as someone else's proprietary software.

Understanding these protections can help you choose a license that best suits your needs.


Benefits of adopting open-source licenses

Adopting open-source licenses offers a range of benefits for engineering teams, organizations, and the broader tech community.

Below are a few of the key advantages:

  • Innovation and collaboration: Open-source licenses allow for a collaborative environment where programmers worldwide can contribute to a project. This can lead to innovative solutions and advancements that may not have occurred within the confines of a single organization. Diverse perspectives and expertise can fuel the creation of robust, versatile, and effective software.
  • Cost-effectiveness: With open-source licenses, organizations can leverage existing software rather than starting from scratch. This not only reduces development time but also saves costs associated with programming, testing, and debugging.
  • Customization and flexibility: Open-source licenses provide the flexibility to modify the code to suit specific needs. Whether it's adapting features, improving functionality, or enhancing user experience, open-source offers unparalleled customization potential.
  • Transparency and trust: By having the source code freely accessible, open-source licenses promote transparency. Users can review the code, understand how it works, and trust the software without fearing hidden functionalities or backdoors. This transparency extends to software metadata as well, providing users with comprehensive knowledge about the software's capabilities, dependencies, and performance.
  • Talent attraction and retention: Many developers are attracted to open-source because of its collaborative nature and the learning opportunities it provides. Organizations that engage with open-source projects can attract talented developers who are passionate about their work and continuous learning.
  • Enhanced security: With many eyes on the source code, vulnerabilities can be spotted and fixed quickly, enhancing the software's security. Furthermore, the public nature of open-source projects allows for a continuous process of peer review, which can lead to more secure and reliable software.
  • Legal protection: Open-source licenses provide a legal framework that governs how software can be used, modified, and distributed. These licenses protect both contributors and users, defining rights and responsibilities and helping avoid intellectual property disputes.


Open-source licenses have truly revolutionized the way we develop and utilize software. They empower developers with the flexibility to use, modify, and distribute code, promoting innovation and collaboration.

Understanding different types of licenses, from the permissive MIT and Apache licenses to the copyleft GPL, and their implications are vital to managing the open-source components within your Software Bill of Materials (SBOM).

Additionally, considering essential factors such as license compatibility, restrictions, requirements, and legal protections when choosing an open-source license will safeguard your project's legality and maintain its open-source nature. This, in turn, contributes to a more comprehensive and reliable Software Bill of Materials.

As the digital landscape continues to evolve, open-source licenses and their role in creating a clear and complete SBOM will undoubtedly play a crucial role in shaping future software development practices.

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What is an open-source license?

An open-source license is a type of software license that allows the source code to be used, modified, and/or shared under defined terms and conditions. This facilitates collaboration and transparency in software development.

What are the main types of open-source licenses?

The main types of open-source licenses include permissive licenses (e.g., MIT, Apache, BSD) and copyleft licenses (e.g., GPL, LGPL). The former offer great freedom in terms of code usage and modifications, while the latter requires any changes to be released under the same license.

How do I choose the right open-source license for my project?

When choosing an open-source license for your project, consider factors like license compatibility, the restrictions and requirements of the license, and the level of legal and intellectual property protection it provides. Each project's needs will vary, so it's important to understand what each license type offers.

What are the benefits of using open-source licenses?

Using open-source licenses promotes transparency, encourages collaboration, and fosters innovation by allowing developers to modify and improve code. Additionally, these licenses can help protect against legal issues and provide opportunities for community support.

What is the role of an open-source license in a Software Bill of Materials (SBOM)?

In an SBOM, open-source licenses help document the licensing terms of each component in a software product. This helps companies avoid legal complications and ensures compliance with various software licensing terms.

Which type of open-source license requires attribution only?

The MIT License and the BSD licenses are examples of permissive open-source licenses that require attribution only. These licenses are simple and have minimal restrictions on what others can do with the licensed software. The main requirement is that the original copyright notice is included in copies or substantial uses of the work.



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