Windows App Runtime (Windows App SDK)

v2.6.4 (stable)FreeReleased 27 Oct 2026

Runtime for modern WinUI 3 apps; fixes 'Windows App Runtime is required' errors. By Microsoft Corporation

Windows

Official sourceNo bundles

By the ToolsBharat teamUpdated 27 Oct 2026How we check

Quick answer

Windows App Runtime (Windows App SDK) is free software for Windows from Microsoft Corporation. Runtime for modern WinUI 3 apps; fixes 'Windows App Runtime is required' errors. Download it only from learn.microsoft.com. The latest version we track is 2.6.4 (stable) (27 Oct 2026). ToolsBharat links straight to the publisher's own download page, with no bundled offers.

Latest version:: 2.6.4 (stable) (27 Oct 2026)
Publisher:: Microsoft Corporation
Official site:: learn.microsoft.com
Licence:: Free — Proprietary — free (source on GitHub)
Requirements:: Windows 10 / 11

Our verdict

Newer Windows apps built with WinUI 3 need this runtime. Most get it automatically from the Store, but an app installed from a website may say a specific Windows App Runtime version is missing. Microsoft's downloads page lists installers for each stable release; get the version the app names, in x64 for most PCs. Entries called 'Windows App Runtime Main' or 'Singleton' in Apps & features belong to this runtime and are safe to keep.

Key features

Standalone installer for x64, x86 and ARM64 per release
Redistributable ZIP with all architectures for offline deployment
Several stable versions listed, so you can match what an app requires
Installs the Framework, Main, Singleton and DDLM packages

Pros

Pro: Official per-version installers
Pro: Fixes WinUI 3 app launch errors
Pro: Release notes linked for every version

Cons

Con: Version numbers matter: apps may need a specific one
Con: Mostly developer-facing documentation

What's new in 2.6.4 (stable)

See what changed in 2.6.4 (stable) in the official release notes

Version history

Version 2.6.4 (stable)Latest
27 Oct 2026
SHA-256
The developer does not publish one
Source
Release notes

Requirements

OS: Windows 10 / 11
Architecture: 64-bit, 32-bit, ARM64

Licence

Type: Free
Licence: Proprietary — free (source on GitHub)
Publisher: learn.microsoft.com

Where these facts come from

Latest Windows App SDK downloads

Checked 30 Oct 2026

FAQ

What is 'Windows App Runtime Main' and do I need it?

It's part of the Windows App Runtime, which apps built with the Windows App SDK (WinUI 3) rely on. Removing it can stop those apps from opening, so leave it installed.

An app says Windows App Runtime 1.x is missing but you list 2.6. What do I do?

Install the exact version the app asks for. Microsoft keeps older releases on its 'Archive of Windows App SDK downloads' page, linked from the downloads page.

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