Definition
Open source is software whose source code is published under a licence that lets anyone use, study, modify and redistribute it, usually free of charge. It is developed in the open by communities, companies or foundations, and it underpins most of modern technology: the Linux operating system, the PostgreSQL database, the Python language, the React framework and the Kubernetes platform are all open source. Nearly every commercial product is built on open source components.
In a company, open source shows up in two ways. Your own software is built on hundreds of open source packages, which cuts development cost dramatically but requires tracking licences and security vulnerabilities. And you may choose open source products, such as databases, analytics tools or AI models, instead of proprietary ones, trading licence fees for the cost of running and supporting them yourself or paying a vendor for a supported version.
Open source is now the default for infrastructure and increasingly for AI, with open-weight models a related but distinct concept. Commercial models around it include paid hosting, support and enterprise features. Supply chain security, meaning checking that the packages you depend on are safe, has become a serious concern. The misconception is that open source means unsupported or risky. The most critical software in the world is open source, and its openness is why it is trusted.
In practice
A company replaced a proprietary database costing six figures a year with PostgreSQL, an open source database, and spent a fraction of that on a managed cloud service to run it. Performance improved and vendor negotiations disappeared.
Why it matters
Open source is why software is cheap to build and why you can avoid vendor lock-in. Understanding what your products depend on, and the licence and security obligations that come with it, is basic technical due diligence.
Frequently asked questions
- Is open source software free?
- The software itself usually costs nothing to use, but running, securing, updating and supporting it costs time or money. Many companies pay vendors for hosted or supported versions of open source products. The saving is real, but it is not zero cost.
- Is open source software secure for business use?
- Generally yes, and often more so than closed software, because anyone can inspect the code and vulnerabilities are found and fixed publicly. The risks are using outdated versions and unvetted packages, so companies should track their dependencies and apply security updates promptly.