Microsoft says that it will make WinUI ‘truly’ open source

Microsoft has announced that it has plans to “truly open sourcing” WinUI, the user interface framework that is embedded in Windows. Although no specific timeframe has been mentioned, the company is “actively working toward it”.

Pointing out that making the WinUI repository open source is not just a “flip-the-switch moment” but a “deliberate process”, Microsoft lead software engineer Beth Pan says that the process is a complicated one. This is part of the reason for not being willing to commit to a specific end date for any particular milestone.

Microsoft is taking a phased approach to open sourcing WinUI, but it does not offer any indication of how long each phase could last.

Setting out its vision of how the process could work, the company says:

Phase 1: Increased Mirror Frequency
After the WASDK 1.8 release (end of August), we’ll begin more frequent mirroring of internal commits to GitHub to increase transparency and show progress.
Phase 2: 3rd Party Devs Build Locally
External developers will be able to clone and build the repo locally, with documentation to guide setup and dependencies.
Phase 3: 3rd Party Devs Contribute & Run Tests
Contributors will be able to submit PRs and run tests locally. We’re working to untangle private dependencies and make test infrastructure publicly accessible.
Phase 4: GitHub as Center of Gravity
GitHub becomes the primary place for development, issue tracking, and community engagement. Internal mirrors will be phased out.

Due to the fact that WinUI is deeply rooted in Windows, Microsoft needs to spend time working out how to extract the elements it is able to share and those that it cannot. The sheer size and compexity of the Windows codebase means that this is something that simply cannot happen quickly, and the need to protect “proprietary layers” requires careful attention.

The open sourcing also needs to be aligned with Microsoft’s existing goals, as Pan explains:

We are being thoughtful about resourcing. This effort is happening alongside other critical responsibilities like security, platform stability, and support for existing products. Our current focus is on foundational work that unlocks value for contributors and increase transparency. We are aligning this work with Microsoft’s broader business priorities to ensure long-term support and impact.

It is hoped that by open sourcing WinUI, it will be possible to speed up the development process and help to take the project in new directions faster than would have otherwise been possible.

Details of what happens next are a little thin on the ground, but Pan says:

We are working on making incremental progress and will share more soon.

The reception from developers is, on the whole, positive although those who are not fans of WinUI in general are – perhaps unsurprisingly – unimpressed.

This decision is just part of Microsoft’s growing willingness to embrace the idea of open source software and the general philosophy of the open source movement.

The company also says:

We are working on making incremental progress and will share more soon. We will start using this project board to work collaboratively with the community on product prioritization. We also commit to better wiki and transparency on monthly planning. We know this isn’t everything you want to hear, but we hope it shows we’re serious about doing this right. We’ll keep sharing updates as we go.

Does this seem like a good idea to you? And do you expect Microsoft to meet people’s expectations when it comes to open sourcing this and other projects?

There is the question of whether Microsoft's lack of commitment to a timeline renders its open sourcing promises rather less meaningful than they might otherwise have been.

Image credit: Alexey Novikov / Dreamstime.com