Open source software is software whose source code — the actual instructions that make it run — is published publicly under a license that allows others to view it, use it, modify it, and often redistribute their own changes. This is the opposite of “proprietary” or “closed source” software, where only the company that built it can see or change the underlying code. Well-known open-source licenses like MIT, Apache, and GPL each set different rules for how the code can be reused, especially in commercial products.

Open source matters to startups in two directions. Almost every modern tech company builds on top of free, open-source components — programming languages, frameworks, and libraries other people have already built and shared — which is a large part of why building software has become dramatically cheaper over the past two decades. Some startups also release parts of their own code as open source deliberately, to build developer trust, attract talent, or drive adoption of a paid “open-core” version with extra features.

A nuance worth understanding: “open source” and “free” are not the same thing. The code may be free to view and use, but many open-source licenses still carry obligations, such as crediting the original authors or open-sourcing your own modifications, and plenty of profitable companies are built entirely around support, hosting, or premium features on top of software that is technically free.

🇵🇭 Philippine Example

Bayanihan Linux, developed since 2001 by the Advanced Science and Technology Institute (ASTI) under the Philippines' Department of Science and Technology, is a real, homegrown open-source operating system built as a lower-cost alternative to proprietary software for Philippine government offices, schools, and small businesses.

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