Discover the Most Common Open Source Licenses in 2023

In today’s rapidly evolving technological landscape, open source licenses are emerging as the unsung heroes of the software development lifecycle. As someone who has represented and advised some of the most innovative companies in the tech and crypto industries, I am well acquainted with the role of legal considerations in the deployment of technology. Navigating the fascinating world of crypto and blockchain, I have seen firsthand the tremendous impact of understanding and selecting the right open source license. It is an essential skill set for leveraging the benefits of open source software, ensuring legal compliance, and robust protection of intellectual property.

My journey from studying Accounting, which I like to call the ‘language of business,’ to a legal expert in the tech industry, armed me with a unique perspective on these matters. I was schooled in the belief that numbers don’t lie, a philosophy I see reflected in the world of blockchain and open source licensing. Just as in accounting, the same principles of accuracy and compliance underpin the complex world of open source licenses.

With a Juris Doctor from the University of Florida, a top 25 law school, I was introduced to the bustling startup ecosystem in Gainesville, where I first encountered high-growth technology companies. This experience was the spark that ignited my interest in the intersection of law, business, and technology.

In this blog post, we’ll delve into the most common open source licenses, their distinctive features, and how to select the most suitable one for your specific project requirements and goals. My background in accounting, my legal expertise in the tech industry, and my passion for crypto will guide our exploration. So, buckle up, and let’s embark on this insightful journey together!

Short Summary

  • Understand open source licenses to choose the right one for your project.
  • Consider factors such as goals, commercial use and compatibility when selecting software.
  • Seek legal advice to ensure adherence to licensing regulations and protect from potential risks.

Understanding Open Source Licenses

Open source licenses function as legal agreements that provide individuals with the ability to interact with software in a variety of ways:

  1. Access, Enhance, and Share: Open source licenses allow users the freedom to access, modify, and distribute the source code of a software without any restriction.
  2. Use, Modify, and Disseminate: The licenses also facilitate the utilization, modification, and distribution of the software code in a manner that aligns with the original author’s intent.
  3. Protection for All Parties Involved: One of the fundamental goals of these licenses is to ensure the protection of both the creators and users from unauthorized and inappropriate use of the software.

Contrarily, proprietary software typically sets limitations on access and modification. Open source licenses not only regulate how third parties can interact with the software code but also aim to strike a balance between innovation and protection by curbing unapproved use.

Open source software represents a paradigm shift toward transparency, community involvement, and knowledge sharing in the realm of software development. It is publicly available software that anyone can inspect, modify, or enhance based on its source code. Given the wide array of open source licenses in existence, comprehending their nuances is pivotal to making informed decisions in software projects.

Open source licenses broadly fall into two categories: permissive licenses and copyleft licenses.

  1. Permissive Open Source Licenses: These licenses offer maximum freedom with minimum restrictions, allowing for the alteration and distribution of the software in nearly any manner imaginable.
  2. Copyleft Licenses: These licenses stipulate that any derivative works must also be open source, effectively creating a chain of open source distribution.

By delving into the specifics of these licenses, we are better equipped to understand their integral role in shaping the landscape of software development, distribution, and usage.

Permissive vs Copyleft Licenses

Permissive Licenses: Also known as “laissez-faire” or “pushover” licenses, permissive licenses do not impose stringent conditions on software use. They typically only require preservation of the copyright notice when distributing derivative works. Renowned examples of permissive licenses are the MIT License and the Apache License. Permissive licenses provide developers with an expansive degree of flexibility. This allows for easier integration with other software components and promotes commercial utilization. It’s a model that embraces pragmatism over ideology, aiming to encourage widespread use and adoption.

Copyleft Licenses: These licenses, like the GNU General Public License (GPL), advocate for the software freedom philosophy. They necessitate full disclosure of the source code and ensure users are granted rights identical to the original author’s. Copyleft licenses are further divided into strong and weak categories. Strong copyleft licenses, such as the GPL, insist that all derivative works adhere strictly to the original licensing terms. Conversely, weak copyleft licenses offer a more lenient approach.

The critical demarcation between permissive and copyleft licenses plays a significant role when selecting the most suitable license for a software project. If your priority is to retain a software’s open-source nature and promote collective participation, copyleft licenses are typically a more fitting choice, as they ensure the perpetuation of software freedom. On the other hand, if your project requires a broader scope of action and the potential for commercial use, a permissive license might be your go-to option. Understanding these nuances can help guide developers in making informed decisions that align with their project goals and values.

Top 5 Most Common Open Source Licenses

In the broad landscape of open source software, a quintet of licenses distinctly emerges as the most frequently adopted. These are:

  1. GNU General Public License (GPL)
  2. MIT License
  3. Apache License
  4. Modified BSD License
  5. Berkeley Software Distribution (BSD) License

Each license provides its own unique set of features and advantages, and some necessitate that derivative works adopt the same license. The following sections delve into a detailed exploration of these licenses, offering a thorough understanding of their individual characteristics and their potential influence on software development, distribution, and usage.

GNU General Public License (GPL)

The GPL, a pioneering copyleft license, insists on keeping any software application based on any GPL component as an open source product. It enforces disclosure of the full source code for any modifications and bestows users with rights equivalent to those of the original author. The GPL’s fundamental aim is to protect software from being privatized while ensuring its continued openness and freedom.

The GPL fosters a collaborative environment by making it mandatory for any modifications to the software to also be released as open-source products. This characteristic makes the GPL an optimal choice for projects aiming to promote community contributions and protect software usage freedom.

MIT License

The MIT License is a permissive license that allows developers to modify and distribute software code with few restrictions. The primary requirement of the MIT License is that distributed programs that utilize the licensed code must include a copyright notice and a copy of the license text. This permissive nature allows developers to:

  • Modify the code
  • Add to it
  • Publish and distribute their own version
  • Sell it

The MIT License’s minimal restrictions make it popular among developers for its flexibility and ease of integration with other open source software licenses and components. Its permissive nature also facilitates commercial use, making it an attractive choice for businesses and commercial organizations looking to leverage open source software without being burdened by stringent licensing requirements.

Apache License

The Apache License, another permissive open source software license, authorizes users to use, modify, and distribute both original and modified versions of the software, subject to the terms of the Apache license. It contributes to the development of robust and enduring software products through collaborative and open source software development practices.

Characterized by its permissiveness, patent rights grants, and clear definitions of program concepts, the Apache License is favored by developers and users. It provides the flexibility to modify and distribute software with limited constraints, fostering innovation and collaboration within the software development community.

Modified BSD License

The Modified BSD License, a permissive open-source software license, allows free usage, modification, and distribution of the licensed program in both source and binary forms, subject to the preservation of the copyright notice, conditions list, and disclaimer. This permissive nature enables the free utilization, alteration, and circulation of the licensed program, which can help open source software projects to flourish and evolve.

Promoting cooperation and code sharing, the Modified BSD License encourages effective development and superior software. Its permissive nature eases the integration of open source components into other software projects, making it an attractive choice for developers seeking a flexible licensing option.

Berkeley Software Distribution (BSD) License

The BSD License, with its two variants— the Modified BSD License (3-clause license) and the Simplified BSD License (2-clause FreeBSD License)—is similar to the MIT License, but adds an additional clause prohibiting the use of the author’s name for endorsing or promoting a modified version of their work without prior written authorization.

As a permissive free software license, the BSD License places minimal restrictions on users and does not impose stringent conditions on the redistribution of licensed open source software. Its flexible nature makes it a popular choice among developers seeking a permissive licensing option.

Choosing the Right Open Source License

Deciding on the right open source license for your project is a crucial task that can influence its future trajectory and success. By considering elements like project objectives, potential for commercial use, and compatibility with other licenses, you can select a license that aligns well with your intentions and needs.

In the subsequent subsections, we will delve into these key considerations and highlight the importance of seeking legal counsel when deciding on the most suitable open source license.

Factors to Consider

When determining the intended use of the software, it is essential to consider:

  • Whether the software will be employed for commercial or non-commercial purposes
  • Whether it will be utilized for open source or closed source projects
  • The degree of control you wish to retain over the software and its source code.

Another important aspect to consider is the compatibility of the license with other licenses, both open source and closed source. Understanding the compatibility of various licenses can help prevent potential conflicts and ensure that your project can be seamlessly integrated with other software components.

Seeking Legal Advice

Selecting an open source license can be complex and fraught with potential legal implications. To ensure compliance with open source licensing regulations and to avoid potential complications, consulting legal counsel is strongly recommended. It’s advisable to work with lawyers who specialize in intellectual property law and have experience with open source licensing. Montague Law, for instance, could provide the necessary expertise and guidance in this area. Engaging a team or individual with extensive knowledge and experience in open source licensing can help ensure that the chosen license is suitable for the project and that all legal obligations are met.

Incorporating legal experts into the decision-making process can help you:

  • Navigate the complexities of licensing terms and conditions
  • Prevent potential issues that could put your valuable intellectual property at risk
  • Ensure that your project complies with all relevant laws
  • Protect your project from potential legal risks

By seeking guidance from expert services such as Montague Law, you can safeguard your project, ensuring its compliance and protection from potential legal risks. Montague Law’s specialized understanding of open source licensing can help you make informed decisions that align with your project’s goals and legal requirements.

Open Source License Compliance and Management

Ensuring compliance with open source licensing requirements is vital for organizations to guarantee that the license types and terms for the open source components used are compatible with the packaging and distribution of their software. In the following subsections, we will discuss best practices for identifying licenses and meeting your license terms and obligations, helping you manage your open source licenses effectively and maintain legal compliance.

Best practices for identifying licenses include researching the license type of each component and verifying the license type.

Identifying Licenses

The process of identifying and understanding the licenses associated with open source components used in a project is crucial for ensuring compliance and avoiding potential issues. Compiling license texts associated with open source components is essential for flagging any components that are not compatible with the software’s distribution and license requirements, or with licenses that may be used by other components in the software.

An open source audit can provide an in-depth understanding of the code’s composition, revealing known security vulnerabilities that impact the open source components, as well as information such as versions, duplications, and the development activity of a component. By identifying the licenses associated with your open source code components and understanding their implications, you can ensure legal compliance and protect your project from potential risks.

Meeting License Obligations

Meeting the obligations imposed by various open source licenses is essential for ensuring legal compliance and protecting your valuable intellectual property. All open source licenses require attribution, so it is important to include the necessary copyright notices and license texts, also known as a license notice, when utilizing open, code commercially other source components in your project.

Tools such as Black Duck software composition analysis (SCA) can assist development, security, and compliance teams in managing the risks associated with the utilization of open source. Black Duck’s KnowledgeBaseTM provides data on over 2,500 open source licenses that may impose restrictions on the software your team develops.

By being aware of these license obligations and taking the necessary steps to meet them, you can ensure the legal compliance and success of your software project.


In conclusion, understanding and selecting the right open source license is crucial for the success of your software project and the protection of your intellectual property. By exploring the most common licenses, such as the GNU General Public License, MIT License, Apache License, Modified BSD License, and Berkeley Software Distribution License, you can gain valuable insights into their unique features and implications. Considering factors such as project goals, commercial use, and compatibility with other licenses, as well as seeking legal advice, can help you make an informed decision and ensure compliance with open source licensing requirements. By effectively managing your open source licenses and meeting license obligations, you can foster innovation, collaboration, and the long-term success of your software project.

Frequently Asked Questions

What is the most common open source license?

The most common open source license is the GNU General Public License (GPL). This copyleft license guarantees developers the freedom to modify programs and distribute them as free software. Ensuring that any software based on any GPL component must be released as open source.

What are the common open source licenses?

Popular open source licenses include the Apache License, MIT License, GPL, LGPL, BSD Licenses, and Mozilla Public License, falling into two broad categories of permissive and weak copyleft license.

The GPL is the most popular copyleft license, preserving license notifications and copyright terms, suitable for commercial, patent, and private use.

What are the four major types of open source licenses?

The four major types of open source licenses are the GNU GPL, MIT, Apache License, and BSD License.

Which is the most restrictive open source license?

The most restrictive open source license is the GNU General Public License (GPL) and the isc license the GNU Affero General Public License (AGPL).

What is the difference between permissive and copyleft licenses?

Permissive licenses allow for modification and distribution of the software without restrictions, while copyleft licenses require any derivative works to be licensed under the same conditions as proprietary code.

What are the advantages and disadvantages of permissive and copyleft licenses?

Permissive licenses, such as the MIT and Apache licenses, offer flexibility to developers as they impose fewer restrictions on how the software can be used or modified. They also facilitate integration with other software and enable commercial use, making them popular among businesses. However, they don’t ensure that derivative works will remain open source, which can limit the collaborative development of the software.

On the other hand, copyleft licenses, such as the GPL, require derivative works to remain open source, fostering collaboration and preserving the openness of the software. However, these licenses can be more restrictive, as they require developers to disclose their source code and can limit the software’s commercial viability.

How can I determine the most appropriate open source license for my project?

Selecting the appropriate license for your project depends on various factors, including your project’s goals, whether you want to allow commercial use of your software, and the need for compatibility with other licenses. It’s advisable to consult a legal expert, such as Montague Law, to navigate the complexities of open source licensing and to ensure that your chosen license aligns with your project’s objectives and requirements.

What legal implications could arise from choosing the wrong open source license?

Choosing the wrong open source license can lead to a variety of issues. If the license is incompatible with the licenses of other software your project depends on, it can prevent you from legally distributing your software. Moreover, if your license does not protect your rights as you intended, it can lead to the unwanted use of your software, such as its incorporation into proprietary software without your consent.

Can I change the open source license of my project at a later stage?

Yes, but changing the open source license of a project can be complex. It usually requires the agreement of all contributors, as they have copyright over their respective contributions. Some projects require contributors to assign their copyright to the project, which can simplify the process. Again, legal consultation is recommended when considering changing the license of a project.

What role does Montague Law play in the process of choosing an open source license?

Montague Law can provide legal guidance and expertise in the realm of open source licensing. Their team can help navigate the complexities of licensing terms and conditions, prevent potential issues that could put your valuable intellectual property at risk, ensure legal compliance of your project, and protect your project from potential legal risks. Their specialized knowledge can assist in making informed decisions that align with your project’s goals and legal requirements.



Legal Disclaimer

The information provided in this article is for general informational purposes only and should not be construed as legal or tax advice. The content presented is not intended to be a substitute for professional legal, tax, or financial advice, nor should it be relied upon as such. Readers are encouraged to consult with their own attorney, CPA, and tax advisors to obtain specific guidance and advice tailored to their individual circumstances. No responsibility is assumed for any inaccuracies or errors in the information contained herein, and John Montague and Montague Law expressly disclaim any liability for any actions taken or not taken based on the information provided in this article.

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