Microsoft unveils open-source tools at Build 2025, including a new CLI text editor and open access to WSL.

Microsoft doubled down on its open-source strategy at Build 2025, unveiling a trio of tools aimed squarely at developers — and promising to make life on Windows more seamless, flexible, and developer-friendly.

The standout announcement is Edit, a new command-line text editor for Windows. Designed for speed and simplicity, Edit allows users to manipulate text files directly from the terminal by simply typing the edit command. Slated to ship with Windows through the Insider Program this summer, Edit seeks to reduce “context switching” — the time-wasting toggling between apps — by letting developers remain focused in their command-line workflows.

“Developers want to stay in the zone,” said a Microsoft engineer at the Build keynote. “Edit gives them that uninterrupted experience, right in the terminal.”

In a further nod to open development, Microsoft is releasing the Edit source code to the public. That means developers can inspect it, adapt it, and even build custom versions — a major shift from Microsoft’s historically closed stance on inbuilt Windows tools.

But the surprises didn’t end there.

Microsoft also announced that GitHub Copilot for Visual Studio Code — its AI-powered coding assistant — will soon be fully open sourced. Originally a proprietary plugin, Copilot uses AI to generate code suggestions in real time. Over the next few months, Microsoft says its capabilities will migrate to the open-source VS Code repository, enabling the community to expand, tweak, or repurpose Copilot’s underlying tech.

This move signals Microsoft’s commitment to open collaboration in AI tooling — a notable step at a time when AI intellectual property is typically guarded.

And in perhaps the most impactful release for system-level developers, Windows Subsystem for Linux (WSL) will also become open source.

WSL, long a favourite among developers needing Linux environments on Windows machines, has allowed users to run native Linux binaries without dual-booting or relying on virtual machines. Open sourcing WSL means that developers and enterprises alike will gain unprecedented flexibility to tailor the subsystem to specific tasks, troubleshoot bugs, or contribute improvements directly.

“WSL has been a game-changer, but open sourcing it is the next evolution,” said one attendee at the Build conference. “It’s about trust and transparency.”

While open-sourcing these tools doesn’t translate into direct revenue for Microsoft, it has clear strategic advantages. Open source acts as both a feedback loop and an innovation lab. By opening the doors to external developers, Microsoft gains access to ideas, bug reports, use cases, and extensions that might otherwise never emerge.

It also tightens Microsoft’s grip on the developer ecosystem — particularly as it continues to promote Windows as a serious platform for software engineering, AI development, and cloud-native tools.

Critics in the past have accused Microsoft of “embrace, extend, extinguish” tactics, especially in developer tools. But in recent years, the company has made concerted efforts to win back trust in the open-source community — including acquiring GitHub, joining the Linux Foundation, and now, releasing core Windows utilities to public repositories.

This year’s Build conference made one thing clear: Microsoft wants to be the home for developers, and it’s willing to tear down old walls to make that happen