“Source available” software, often licensed under what’s called a Business Source License (BSL), looks deceptively similar to open source. At first glance, you get access to the source code – but your rights to use, modify, and distribute it are tightly restricted. Unlike true free software, these licenses do not guarantee freedom. Instead, they are a way for companies to market themselves as open while keeping firm control over how their software is used.
A textbook example is found in several popular databases that shifted from free licenses to source-available models (e.g., MongoDB, MySQL, etc.) These companies publish their code publicly, but limit its use in production environments or forbid competitors from offering hosted services based on it. In short, you can read the code, but you can’t freely use it. That isn’t open source – it’s open washing!
The same bait-and-switch appears elsewhere. Take Docker, the widely known container management platform. While Docker’s underlying engine is free software under the Apache license, its client requires users to agree to a restrictive End User License Agreement (EULA). This dual approach lets Docker present itself as open while still pulling users into a closed ecosystem.
If you value freedom and long-term reliability, it’s always worth considering free alternatives. One strong replacement for Docker is Podman, developed by Red Hat (IBM). Podman is a drop-in replacement for Docker that not only preserves your freedoms but also improves security through its architecture. By avoiding a central daemon, Podman reduces the attack surface substantially – making zero-days and other vulnerabilities far less common compared to Docker.
It’s also worth looking at Kubernetes, the leading container orchestration system. Unlike Docker’s client, Kubernetes is fully free software under the Apache 2.0 license and governed by the Cloud Native Computing Foundation (CNCF). Its development is community-driven, meaning no single company has unilateral control over its future. Kubernetes demonstrates that large-scale, enterprise-grade projects can thrive as true open source, with transparent governance and broad industry collaboration – proving there’s no need to accept “source available” compromises.
One of the most effective ways to prevent this misunderstanding from spreading is to license your code under a copyleft license, like the GNU General Public License (GPL). Critics sometimes argue that copyleft can limit a project’s growth because of its strict rules on how the code may be used and redistributed. However, the GPL remains the most thoroughly tested open-source license in legal history. Multiple high-profile cases involving major industry players have confirmed not only the GPL’s validity as a licensing framework, but also the enforceability of its requirements.
By choosing a copyleft license, you can further reinforce this distinction by referring to your project as “Free software” or “Libre software,” helping set it apart from the broader open-source ecosystem. Be wary of software marketed only as “open source” – it may be open washed! It might look like open source, but it doesn’t respect the principles of free software. If freedom, security, and transparency matter to you, stick with genuine free tools under free licenses.