Microsoft's Open Source Journey: The Cultural Transformation from TypeScript to VS Code

Microsoft was long viewed as the antithesis of the open source world — yet over the past decade-plus, the company has undergone a profound transformation. From its earliest steps of redistributing jQuery in ASP.NET, to fully open-sourcing TypeScript, Chakra, .NET, and Visual Studio Code, what changed inside Microsoft wasn't just a series of technology decisions. It was a complete cultural reinvention. A senior Microsoft engineer who was deeply involved in this journey looks back on the years-long process of bringing core developer products into the open source community.

Where It Started: From Redistributing jQuery to Building TypeScript

Microsoft's open source practice didn't begin with the posture of "contributing code." The real starting point was entirely pragmatic — supporting and redistributing jQuery inside ASP.NET. This wasn't about Microsoft building jQuery; it was simply about integrating a popular front-end library into their own framework so developers could benefit from it directly.

This "borrow and leverage" approach laid the psychological and organizational groundwork for deeper open source engagement to come. The true turning point was the release of TypeScript. The team recognized that a language designed for broad adoption by the JavaScript community simply had to be open source — otherwise it could never earn the community's trust or contributions. A language's success depends heavily on its ecosystem, and a closed technology would struggle to find its footing in the open world of JavaScript.

TypeScript was first publicly released in 2012 as a Microsoft-designed superset of JavaScript. By adding a static type system and compile-time checking, it improves the maintainability of large-scale projects while compiling down to standard JavaScript that runs in any JS-compatible environment. The decision to open-source TypeScript was strategic: the JavaScript community had long cultivated an open, decentralized culture, and a proprietary language controlled by a large corporation would have a hard time earning community trust — let alone being integrated into third-party frameworks and toolchains. The strategy proved correct. Major frameworks including Angular, Vue, and React all adopted TypeScript as a first-class citizen, and TypeScript has since become one of the de facto standards of front-end engineering.

Shrinking Approval Cycles: An Invisible Cultural Revolution

Pushing TypeScript into open source wasn't easy. According to this engineer, simply convincing company leadership — jokingly referred to as the "muckety mucks" — to approve the open source release took roughly six months, involving extensive internal discussions about both the "how" and the "why."

What truly illustrates the cultural shift isn't any single open source decision, but the dramatic reduction in how long approvals took. Just a few years later, when the team decided to open-source Chakra — the JavaScript engine that powered Internet Explorer — the time from proposal to approval shrank by orders of magnitude compared to the TypeScript experience.

The contrast is striking. Both cases involved open-sourcing core technical assets, yet the enormous difference in decision-making speed directly reflects a fundamental shift in how Microsoft viewed open source internally: it was no longer an exception that required layers of justification, but was gradually becoming the default.

Chakra was the JavaScript engine Microsoft developed for Internet Explorer and early versions of Edge. It was open-sourced on GitHub in 2016 under the name ChakraCore. A JavaScript engine is a browser's core competitive asset — responsible for parsing, compiling, and executing JS code, with a direct impact on web performance. Before Chakra, Google's V8 (used in Chrome and Node.js) and Mozilla's SpiderMonkey were the leading examples of open source JS engines. Microsoft's decision to follow suit was partly about winning goodwill from the developer community and partly about leveraging external contributions to improve engine quality. The open-sourcing of ChakraCore signaled Microsoft's willingness to expose foundational technology that had once been considered a core competitive moat — something that would have been nearly unthinkable just a few years earlier.

From .NET to VS Code: The Logic Behind Modern Developer Products

The open source momentum didn't stop at languages and engines. Microsoft went on to bring .NET into the open source world, and from the very beginning built Visual Studio Code in the open. These two cases represent a more mature open source philosophy — not building in private and releasing later, but developing directly in a public environment from day one.

The success of VS Code is perhaps the clearest validation of this logic. It is now one of the most widely used code editors in the world, and its massive extension ecosystem and vibrant community owe much to that open development model. As this engineer puts it, modern developer products need to be "built in the open" — when products are built as open source, they tend to accumulate loyal user bases more readily, and they often end up being better products.

.NET's open source journey was equally significant. Microsoft announced .NET would go open source in 2014 and released the cross-platform .NET Core in 2016, breaking the long-standing limitation of .NET being Windows-only. Part of the driving force was competitive pressure in the cloud computing market — Linux is the dominant operating system on the server side, and if .NET couldn't run cross-platform, Microsoft would be unable to compete with Java, Go, and others in the cloud-native era. Visual Studio Code, by contrast, was built from scratch in open source mode, developed on the Electron framework with its codebase hosted on GitHub and open to community pull requests. This "born open source" development model helped VS Code accumulate over 30,000 extensions within a few years of launch, with monthly active users surpassing tens of millions — making it one of the fastest-growing developer tools in history.

Why Open Source Makes Products Better

Underlying this retrospective is a product philosophy worth sitting with: the value of developer tools comes in large part from community trust, contributions, and co-creation. For products aimed at developers, transparency and openness aren't marketing talking points — they're a core component of competitive advantage.

Open source means developers can audit the code, submit fixes, contribute features, and even extend the product for their own needs. This bidirectional interaction continuously refines the product against real-world use cases, creating a positive feedback loop. Microsoft's journey from redistributing jQuery to open-sourcing VS Code is, at its core, an evolution from "giving developers technology to use" to "building technology together with developers."

For any team thinking through a technology product strategy, this story offers a clear reference point: cultural change is almost always harder than technical decisions, but once an organization truly embraces the value of openness, open source stops being a special exception that requires repeated approval — and becomes the natural choice that drives product success.