How Microsoft uses GitHub

Microsoft's engineers maintain TypeScript, .NET, Windows Terminal, Dapr, Helm, and more than a thousand other open source projects. The company has scaled its participation in open source on GitHub from 2,000 to 25,000 engineers, sharing work with the larger developer community whether through samples, small projects, or SDKs.

From proprietary to open source

Decades ago, Microsoft held tight to their intellectual property and was known in part for opposition to open source. But as open source redefined how software was built, the company faced a critical moment. In the 2010s, they fundamentally rethought their approach to open software and became one of the largest contributors to open source in the world.

Microsoft's evolution wasn't primarily technical but philosophical. A decade ago, the company kept their IP close to the chest. "We couldn't give up our secret sauce, right?" said Jeff Wilcox, Principal Software Engineer in the Open Source Programs Office (OSPO). "Our evolution wasn't about drastically changing our technology, but about rethinking the value we could provide."

At first, Microsoft's open source engagement happened in measured steps as they tested new processes. They released software under their own licenses, then gradually embraced MIT licensing. Now even once tightly closed code like .NET is open source under an MIT license. "We decided to embrace what the industry was doing," Wilcox said. "Today, developers expect all of these pieces to be open source by default. They wouldn't use .NET Core if it was proprietary. Teams realized that they need to accept contributions to get feedback, learn from developers, and move forward."

The Open Source Programs Office

To organize and formalize their approach across a global staff of more than 140,000, Microsoft created their Open Source Programs Office (OSPO). "At Microsoft, open source is endemic," explained Wilcox. "Tens of thousands of open source packages are used in millions of different ways—nearly all of our work depends on it, everywhere in the company. The OSPO enables us to centralize our knowledge, distribute information, and collaborate coherently."

The OSPO's mission is to democratize and scale open source use and contributions within the company, not limit them. "We're not gatekeepers or police," Wilcox said. "We're facilitators: We eliminate unnecessary roadblocks and simplify open source process for all teams." The OSPO works closely with Microsoft's legal, security, and business organizations to make processes as self-serve as possible, ensuring that all information and policies groups need to make independent decisions are readily accessible and tooled back into the engineering system.

ClearlyDefined

As part of this initiative, Microsoft started ClearlyDefined, an OSI project that crawls all open source projects to discover license, copyright, and other data, curating and sharing it in the open. For Stormy Peters, Director of Microsoft's OSPO, ClearlyDefined is about data-driven knowledge sharing across the entire open source community. "We want to collaborate with other companies and individuals to bring transparency and compliance to open source licensing," she explained. "And we'd love to make sure that any information we find goes back upstream. If a project with an MIT license has GPL license code, for example, we'd like to let the maintainers know, so they can update their license information if they choose to."

Supporting open source projects

The OSPO provides resources and information maintainers need to manage thousands of repositories and contributors effectively on GitHub. Although Microsoft invests in their own tooling when necessary, they increasingly look to other individuals and organizations leading the way. The team has invested in open services and systems to make it easier to collaborate with other companies and their preferred tech stacks, and has invested in other companies' projects like SAP's CLA Assistant or Amazon's open source attribution engine to support internal open source contributors and consumers.

Releasing open source projects

Microsoft's current approach to releasing open source projects is focused on developer experience. The team identifies software that already benefits users and makes it available in its most useful format. For example, the team behind Microsoft Graph open sourced the core collaboration graph under Office. Open sourcing projects people use every day also gives them the opportunity to iterate and have a direct impact on their tools.

This process varies from project to project. Peters rejects the idea of a one-size-fits-all open source release, instead asking questions around user relevancy, project and business goals, and metrics for success. "Every project we open source has different goals," she said. "We open source some complete projects without the expectation of increasing engagement or building a community. Others are released as open source to build a community outside of Microsoft."

Visual Studio Code exemplifies the benefits of this approach. "Whether they want to suggest a fix or just build a different experience, developers can participate on GitHub through issues and pull requests," said Wilcox. The Visual Studio Code team benefits from engaged contributors and development in the open, building a community of co-creators where issues, discussions, roadmaps, and iteration plans are discussed publicly, enabling direct feedback from the people most invested in their software.

Why GitHub

Throughout their open source evolution, Microsoft has turned to GitHub. For Peters, GitHub's value isn't in any one feature but in its community. "GitHub is the place to collaborate," she said. "It's where everyone is and where most of the world's open source is already happening. It's not just a feature, but the whole thing."

Peters also appreciates the instant connection with a global developer community GitHub provides. "It's nice to see who you're working with, to visit their profiles and see what else they've done or what they're interested in," she said. "But GitHub can also function as a resume or a portfolio. It's both an engineering system and a social platform."

Growing their open source presence has opened up the company's software to a world of contributors and to potential talent across the globe. "Candidates tell us that they might not have thought of working at Microsoft before," Wilcox said. "It's not just about open source but also a sign of a profound change to a more open and engaged culture. They see us work in the open, and rethink what it might be like to work here, too."

The broader impact

With the breadth and availability of open source software, it's no longer practical to build every piece of proprietary software from scratch. "But more importantly, open source is about building something that you could have never built yourself," Wilcox said.

Peters has seen a transformation in how people build software throughout her career. "Twenty years ago, you could learn to code without much help from anyone else," she said. "Now projects are no longer driven by just one individual but a group of people. And enterprises can adopt open source models to more effectively work together. At Microsoft and beyond, it's all about individuals coming together in new ways to solve much bigger problems than they could before."