Microsoft announces Project Reunion, its latest attempt to unify the Windows developer platform by reducing fragmentation between Win32 and UWP APIs

At Build 2020 today, Microsoft unveiled Project Reunion, its latest attempt to unify the Windows developer platform by reducing fragmentation …

VentureBeat 2020-05-20 Emil Protalinski

Context & Ripple Effects

Project Reunion is the latest chapter in a decade-long arc: Microsoft's four desktop-to-UWP bridges from 2015 failed to move the app ecosystem, and by 2019 Kevin Gallo was openly describing the company's effort to undo the divide between UWP and Win32, shipping interim patches like XAML Islands and React Native support along the way.

What changed at Build 2020 is framing: rather than asking developers to migrate to UWP, Microsoft now proposes letting both API families converge into one callable surface — an admission that the store-first Universal Windows strategy of the bridge era did not win the desktop.

First-order effects

Windows developers no longer have to choose between Win32 and UWP when starting a new desktop app; the same binary can call modern APIs without a full rewrite into the older model.

Second-order effects

Third-party framework vendors building around the fragmentation — wrapper layers and interop tooling that exist because of the split — face pressure as the gap they monetize closes.

Third-order effects

The 2025 reorganization pulling Windows engineering under a single leader reverses the 2018 team split that mirrored the API split, suggesting Microsoft treats platform unification as an organizational problem, not just an SDK problem; whether Reunion finally sticks where the 2015 bridges did not remains the open question.

The trend: Windows development is consolidating toward a single unified API surface after years of parallel Win32/UWP stacks, with Microsoft repeatedly restructuring teams and SDKs to force the merge.

Discussion

@tomwarren Tom Warren on x
Microsoft is unveiling its Windows Project Reunion today. It's a plan to unify Windows desktop (win32) and UWP apps, and involves unifying existing APIs and decoupling them from the OS. Big news for Windows devs. Details here: https://www.theverge.com/... https://twitter.com/...
@tiraniddo James Forshaw on x
Clearly it should have been called Project COMmunion. https://blogs.windows.com/...
@tomwarren Tom Warren on x
so Microsoft's UWP is finally dead... but so is win32. For Microsoft it's now just “Windows apps” as the company tries to merge the two together with Project Reunion https://www.theverge.com/...
@rudyhuyn Rudy Huyn on x
Introducing Project Reunion! UWP apps and Win32 apps will have access to the same features! Developers will simply have to decide if they want to run on Desktop only or on all Windows 10 platforms! https://twitter.com/...
@withinrafael Rafael Rivera on x
The existing efforts to kill the original UWP walled garden vision and decouple some APIs from the OS (e.g. WinUI) now has a name — “Project Reunion” https://github.com/... Nothing particularly new here.
@epro Emil Protalinski on x
“We're bringing together the combined power of Win32 and UWP. So developers no longer have to choose, because we're unifying these existing APIs — in some way decoupling them from the OS.” #MSBuild https://venturebeat.com/...
@stroughtonsmith Steve Troughton-Smith on x
Another year, another Windows app platform upheaval 😅 Incidentally, as Apple has so far followed Microsoft's lead w/ UWP, I imagine they'll unify Catalyst+AppKit in much the same way as MS' ‘Project Reunion’. Not iOS, Catalyst, AppKit apps, just ‘apps’ https://www.theverge.com/..…
@dotnet @dotnet on x
With .NET 5, we begin our journey of unifying the .NET platform, bringing .NET Core and Mono/Xamarin together in one base class library and toolchain. ‼️ Introducing .NET Multi-platform App UI (.NET MAUI) ‼️ Learn more: https://devblogs.microsoft.com/ ... #dotnet #MSBuild https:/…
@codemillmatt Matthew Soucoup on x
If you're doing Xamarin development - go read this blog about the evolution of Forms ... MAUI (best name ever) ... amongst other things - a _single_ project for everything & MVU (but only if you want) https://devblogs.microsoft.com/ ...
@jeremydmiller @jeremydmiller on x
At a first glance, MAUI actually looks interesting to me: https://devblogs.microsoft.com/ ... But only if the MVU style w/ hot reload is really a first class citizen.
@jamesmontemagno James Montemagno on x
It has been a long journey and I am pumped for the next evolution of Xamarin that we are announcing today, Maui, the .NET Multi-platform App UI framework enabling developers to create beautiful native apps across mobile & desktop. Info, plans, & roadmap https://devblogs.microsoft…
@qmatteoq Matteo Pagani on x
Say hello to Project Reunion! A new vision to unify and evolve the Windows developer platform, breaking down the barrier between Win32 APIs and UWP APIs. Follow the Microsoft 365 keynote coming later at #MSBuild to know more! #Windows10 https://blogs.windows.com/...
@panos_panay Panos Panay on x
Today, we are introducing Project Reunion - our vision for unifying app development across the billion @Windows 10 devices. Check out @kevintgallo's blog to learn more #MSBuild https://twitter.com/...
@epro Emil Protalinski on x
“We are seeing a 75% increase in the minutes spent on Windows 10 in a month. This translates to a rich opportunity for developers to create both new applications and extend the reach of their existing applications.” Microsoft CEO @satyanadella at #MsBuild https://venturebeat.com/…
@dcseifert Dan Seifert on x
what goes around goes around goes around comes all the way back around https://twitter.com/...
@ow @ow on x
Wow, Microsoft ‘Project Reunion’ seems like a big deal. Finally unifying old-school Windows apps and modern apps/Progressive Web Apps with one framework https://www.theverge.com/...
@reyammer Yanick Fratantonio on x
Windows package manager! I dream of a world where people will not need to 1) google for “winrar download” 2) somehow need to guess which one is the legitimate website 3) get compromized over and over again https://devblogs.microsoft.com/ ...
@film_girl @film_girl on x
Also, I love that Windows is getting its own native version of what is essentially homebrew. Meanwhile, I'm very concerned with my ability to install my tools in the next version of macOS since it'll drop built-in versions of Python, Ruby, etc. https://devblogs.microsoft.com/ ...
@benlower Ben Lower on x
Glad to see @ClintRutkas still shipping things for Build! https://www.theverge.com/...
@dcseifert Dan Seifert on x
pow-pow-power toys https://twitter.com/...
@tomwarren Tom Warren on x
Microsoft is launching its new PowerToys Run launcher for Windows 10 today. It's similar to Spotlight for macOS, but the plan is to make it powerful with custom plugins like Alfed for Mac supports. Details here: https://www.theverge.com/... https://twitter.com/...
@radeon Radeon RX on x
AMD is proud to be a part of the democratization of machine learning with the upcoming addition of GPU-accelerated #ML training in Windows on a broad range of #DirectX12 GPUs. Learn about this exciting initiative @Microsoft announced at #MSBuild: https://devblogs.microsoft.com/ .…
@stroughtonsmith Steve Troughton-Smith on x
Fascinating to see Microsoft open up the DirectX 12 API surface to Linux apps running on Windows 10 https://devblogs.microsoft.com/ ... https://twitter.com/...
@nixcraft @nixcraft on x
DirectX is coming to the Windows Subsystem for Linux https://devblogs.microsoft.com/ ... No. It is not for Linux desktop to play games. It is for developers to run ML/AI stuff.
@gunnarmorling @gunnarmorling on x
Perhaps I was too conversative with my 5 years estimate for Windows becoming a Linux distro 🤣? https://twitter.com/... https://twitter.com/...
@ow @ow on x
Oh wow, WSL2 can now run full Linux GUI apps with GPU acceleration as well. Wild https://devblogs.microsoft.com/ ... https://twitter.com/...
@carcinloring @carcinloring on x
Big if true! I wouldn't need to dual boot anymore. https://www.theverge.com/...
@emangare Eduardo Mangarelli on x
Microsoft: “we were wrong about open source”, Microsoft has embraced open source and even Linux in recent years https://www.theverge.com/... > It has been amazing to walk through this open-minded transformation @eglinsky @DiegoBek @scopeta @amartino @mfelman https://twitter.com/.…
@dosnostalgic Anatoly Shashkin on x
So... What can this potentially mean for me? Does this mean Wine is gonna be available *and* hardware accelerated? Because Wine supports Win16 applications iirc. So potentially this means an easily accessible way of running Win16 stuff on my 64 bit Windows machine, right? https:/…
@koush @koush on x
you know the end times are near when it is finally the year of linux on the desktop https://www.theverge.com/...
@eevee @eevee on x
amazing. incredible. i, someone who was born 24 hours ago, cannot imagine how microsoft reimplementing a popular open source thing could possibly in any way be bad https://twitter.com/...
@cabbagebrains @cabbagebrains on x
big news for windows backwards compatibility https://twitter.com/...
@richturn_ms @richturn_ms on x
Big news dropping out of #Build2020. You asked, we heard you! https://twitter.com/...
@tobi_lehman @tobi_lehman on x
Now I can finally run Konqueror on Windows. The year of the Linux desktop is finally upon us https://twitter.com/...
@mcclure111 Mcc on x
I was going to make some joke like “you can run all your favorite Linux GUI apps, such as... Wine!” but having access to the GPU actually is a really big deal for reasons unrelated to GUI so ok I guess I don't have a joke https://twitter.com/...
@whatthebit Stefan Constantine on x
Microsoft is turning Windows into Linux. I am confusion. https://twitter.com/...
@tomwarren Tom Warren on x
Microsoft is bringing Linux GUI apps to Windows 10 and GPU hardware acceleration support. Some really solid improvements coming to WSL for developers. Details here: https://www.theverge.com/... https://twitter.com/...
@backlon Dieter Bohn on x
[insert year of the linux desktop joke here] https://twitter.com/...

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