FluentCleaner for Windows 11: Transparent WinUI 3 Cleanup Using winapp2.ini

A sleek new open-source cleanup utility for Windows 11 hit GitHub on April 3, 2026. FluentCleaner, built with WinUI 3, taps into the power of the community-maintained winapp2.ini ruleset to scrub away junk files with a transparent, modern interface that feels right at home on Microsoft’s latest OS. The developer behind it, known for the FlyOOBE customization tool, crafted FluentCleaner to fill a gap left by aging system cleaners that cling to legacy design languages and opaque scanning logic.

Windows users have long relied on third-party cleaners like CCleaner to reclaim disk space and purge temp files, logs, and browser caches. But many of these tools ship with telemetry, bundled bloat, or questionable default behaviors. FluentCleaner takes a different path: it’s fully open source (MIT license), integrates only with the winapp2.ini ruleseta sprawling, volunteer-updated list of known file locations for junk across thousands of appss, and presents results in a clean, acrylic-backed UI that adheres to Windows 11 design guidelines.

What Exactly Is FluentCleaner?

FluentCleaner is a WinUI 3 desktop application designed exclusively for Windows 11 (build 22000 and above). It weighs in at under 5 MB when installed, relying on the native Windows App SDK to provide cloud-driven updates, Mica material, and high-DPI scaling. The app does one thing and does it well: it scans user-defined areas of the file system and registry based on detection rules from winapp2.ini, then lets you review and delete the matches in one click.

At launch, the tool supports over 2,400 rule entries that cover everything from Windows Update leftovers and error reports to Adobe Creative Cloud caches, Visual Studio build artifacts, Steam download caches, and even Teams logs. Because the rules are maintained by a dedicated community in the winapp2.ini repository, FluentCleaner can ship with a lightweight core and pull updated definitions from GitHub on every launchor check for updates manually.

“I built FluentCleaner because I wanted a cleaner that respects both my privacy and my eyes,” the developer, who goes by the handle mepersonally, wrote in the initial GitHub release notes. “FlyOOBE showed me how much Windows users care about native aesthetics; this is the logical next step.”

How the winapp2.ini Integration Works

Winapp2.ini started as an add-on for CCleaner, providing advanced users with thousands of additional cleaning locations that the built-in rules didn’t cover. Over time, it became the de facto standard for defining what qualifies as “junk” on a Windows machine. The file uses a simple INI format where each entry specifies a display name, a set of file paths or registry keys, and optional detect criteria.

FluentCleaner parses this file directlyno intermediary scripts or proprietary databases. When you open the app, it either loads a bundled copy of winapp2.ini (shipped with the current stable release from the winapp2.ini maintainers) or downloads the latest master branch from GitHub if you have an internet connection. Users can also manually point it to a custom .ini file.

The parsing engine is built in C# using .NET 8 and the Windows App SDK. It handles the complexity of expanding environment variables, checking file existence for detect clauses, and aggregating results by logical cleanup group. The UI then renders each rule as a toggleable card, showing the estimated space savings, which you can drill into for a file-level preview.

Design That Blends Into Windows 11

FluentCleaner’s most striking feature is its visual design. The app spreads its content across a title bar with full Mica backdrop, a side navigation pane for scanning, results, settings, and a log section. Fluent’s Accent Color is picked up from your system settings, and context menus use the new Windows 11 rounded-corner, shadow-heavy style.

Transparent layering plays a functional role, not just an aesthetic one. Scanning results appear in a semi-transparent list view that lets you see your desktop underneatha subtle cue that the tool isn’t hiding what it’s doing. The progress animation during a scan pauses an acrylic blur circle that fills in clockwise, a design pattern borrowed from the Windows 11 setup experience.

Every interaction responds with the 60fps fluidity that WinUI 3’s composition engine enables. Even on machines with integrated graphics, resizing the window or scrolling through thousands of scan results remains jank-free. The developer credits the Windows App SDK’s new composition support and careful use of virtualization for the large list of potential junk files.

Installation and First Scan

Getting FluentCleaner up and running takes less than a minute. Head over to the GitHub repository (fluentcleaner/FluentCleaner) and download the latest .msixbundle from the Releases section. Because it’s packaged as a Windows App SDK application, you need to have the Windows App Runtime installedit’s included automatically in Windows 11 24H2 and later, but earlier builds may get it via the Visual C++ Redistributable.

Once installed, the app asks for permission to access your documents and downloads folders, as well as the recycle bin location. It doesn’t require administrator privileges for most scans; elevated rights are only needed if you want to clean system-protected areas like Windows Update delivery optimization files or event logs. This least-privilege approach is a breath of fresh air compared to tools that insist on running with full admin rights from the get-go.

Launching your first scan: select the categories you’re interested in (the default is a conservative set that excludes browser passwords and custom detection rules likely to hit false positives). Hit the “Analyze” button, and the app will enumerate all matching files and registry entries, tally up the reclaimable space, and display results hierarchically. You can then choose to clean everything or individually skip items. A post-clean log details exactly what was deleted and from where, with a “Restore” capability for the last operation by moving items to a quarantine folder rather than permanently deleting them.

Safety and Community Confidence

Relying on an externally maintained ruleset sounds risky, but winapp2.ini has a mature trajectory. Since its inception in the late 2000s, it’s been scrutinized by thousands of power users and software developers. Rules that cause problems are quickly flagged and removed; the current maintainers review pull requests with care. FluentCleaner never removes anything from untrusted paths unless the rule includes a known, verified detect signature.

Additionally, the app warns you before cleaning anything that requires elevated privileges or that matches patterns known to occasionally flag legit user data (e.g., certain game save files). A built-in “Smart Skip” feature cross-references each detected file with a small database of known false positives culled from winapp2.ini community feedback over the years.

Because the source code is open, anyone can inspect the parsing logic and cleaning routines. The project’s GitHub Actions workflow runs static analysis and an automated test suite that verifies the parser against a large set of sample .ini files, ensuring that future updates won’t suddenly break detection or cause unintended deletions.

How It Compares to Other Cleaners

The table below sums up the key differentiators between FluentCleaner and two popular alternatives: CCleaner Free and Windows’ own Disk Cleanup / Storage Sense.

FluentCleaner doesn’t aim to replace Storage Sense, which is suitable for basic, set-and-forget temporary file removal. Instead, it targets enthusiasts and IT pros who want granular control, audit trails, and the assurance that no data leaves their machine. The absence of any analytics or license checks makes it a favorite among privacy-focused communities.

Early Reception and Windows Forum Buzz

Within hours of its GitHub debut, FluentCleaner trended on Hacker News and several Windows subreddits. Users praised the eye-candy UI and the fact that the application’s memory footprint stays under 80 MB during active scanninga stark contrast to Electron-based alternatives that easily consume ten times that.

Windows forum regulars noted that the integration of winapp2.ini into a native WinUI 3 shell is a long-awaited marriage. “Finally, a cleaner that doesn’t look like it was abandoned in the Vista era,” wrote user tenforum_au in a thread titled “FluentCleaner: Best looking junk cleaner for 11?” The sentiment was echoed by IT administrators who manage hundreds of machines: “Portable command-line mode + winapp2.ini means we can script it in our deployment pipelines without touching the GUI.”

Criticism has been minimal but constructive. Some early adopters encountered issues with the parser choking on certain Unicode characters in the winapp2.ini file when downloaded directly from the repo with Git line endings. A fix landed within 48 hours (version 1.0.1), and the developer added an option to force download the raw file from the mirror endpoint.

Another request surfaced repeatedly: better integration with Windows’ built-in cleanup scheduling. Several users suggested that FluentCleaner could register itself as a Storage Sense plug-in, making it appear in the Settings app under “Cleanup recommendations.” The developer marked this as under consideration and pointed to the open issue tracker on GitHub.

What’s Next for FluentCleaner?

The roadmap on GitHub outlines a few near-term goals:

• Delta updates: Instead of fetching the entire 1.2 MB winapp2.ini file every launch, a diff-based system could save bandwidth while ensuring freshness.
• Plugin model: Allow third-party rule packs beyond winapp2.ini, such as specialized sets for game development or creative tools.
• Microsoft Store availability: Once the required identity and signing aspects are ironed out, a Store listing could make installation one-click for casual users.
• Multi-language UI: The app currently defaults to English; volunteer translators have already begun submitting localization PRs.

Longer term, the developer hinted at a possible integration with Winget, enabling users to install both FluentCleaner and its rule dependencies with a single command. “We’re also exploring a companion service that runs weekly scans silently and sends a toast notification only when actionable cleanup is advised,” they mentioned in a Q&A thread.

Should You Switch?

If you’re currently using an old version of CCleaner or rely solely on Storage Sense, FluentCleaner offers a refreshing alternative that respects user autonomy and modern Windows design. The reliance on winapp2.ini means it will never lack coverage for obscure apps, and the permissive license guarantees you can fork and modify it to suit your fleet.

The tool isn’t for everyone. Users who prefer a completely automatic, behind-the-scenes cleaner should stick with Storage Sense. And those who absolutely need real-time monitoring and automatic cookie cleaninga feature that has been a privacy minefield in the pastmay find FluentCleaner too manual. But for the rest of us, it’s the kind of righteous utility that Windows 11 deserves.