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Developer Sara Gordic has published Window Sweaters, a Mac app that decorates app windows with knitted-style borders and app-inspired colors. It supports macOS 13 or later, but is not yet notarized by Apple, and the developer warns that it uses private macOS window APIs that could be affected by system updates.
Developer Sara Gordic has released Window Sweaters, a Mac utility that adds knitted-style borders to application windows, with colors and patterns users can customize from a menu-bar control. The app is available through GitHub and Homebrew, but is not yet notarized by Apple, and its creator says it relies on private macOS window APIs that may be affected by system updates.
Window Sweaters lets users choose between a By App style, which gives applications individual colorways, and Zigzag, which applies a shared cream zigzag pattern using colors derived from app icons. The menu-bar yarn icon opens controls for the pattern, border width and stitch size, as well as options to pause or quit the app. Users can turn the effect off for selected apps or disable it across all apps and then enable it only for chosen ones.
The developer says the app includes custom sweaters for 37 applications, with hand-picked colors and patterns. The list spans Apple apps such as Finder, Safari and Terminal; work tools including Slack, Zoom and Microsoft Teams; coding and AI apps such as Cursor, VS Code, Claude and ChatGPT; and design and office software. For other apps, Window Sweaters can sample icon colors locally and use them to create a border. If it cannot find a usable icon color, it uses a stable color based on the app’s name.
Users can install the app using Homebrew, download a ZIP from the project’s GitHub releases, or build it themselves. Gordic says macOS may ask for Accessibility permission so the utility can track which window is focused. If the system blocks an installation, the project instructions direct users to the relevant Privacy & Security settings and explain that the app is not yet Apple-notarized.
A Personalization Tool With Trade-Offs
Window Sweaters is a small customization utility rather than a change to macOS itself: its borders sit around app windows, and users can disable the effect per application or pause it altogether. The range of styles and app-specific colorways gives Mac users a way to alter the desktop’s appearance without changing each app’s own interface.
Installation also involves considerations that do not apply to a standard notarized Mac app. The project says users may need to approve it in Privacy & Security and grant Accessibility access. Its use of private window APIs adds uncertainty about how reliably it will work as macOS changes. Those limitations matter to anyone deciding whether to install a utility that interacts with other apps’ windows.
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How the Window Borders Work
Gordic describes Window Sweaters as a small app built for use on the developer’s own Mac and labels it a work in progress. The project says it supports macOS 13 or later on both Apple Silicon and Intel Macs. However, the developer reports hands-on testing on Apple Silicon with macOS 26 and says older macOS versions and Intel machines have not received the same level of testing.
The project credits JankyBorders, an existing window-border tool by Felix Kratz, as a component used in the app, and says Window Sweaters is released under the GPL-3.0 license. Its customization files allow users to set app colors and replace built-in patterns with PNG charts. The settings remain in a support folder named “Knit Borders,” which the project says is retained so existing settings continue to work.
Compatibility and Security Questions
The project does not provide independent testing or a guarantee of compatibility across Mac models and macOS versions. Gordic says testing has focused on Apple Silicon running macOS 26; the level of testing on Intel Macs and older supported macOS versions is limited. Because the app uses private window APIs, future operating-system updates could change its behavior.
Apple has not notarized the app, according to the installation instructions. The project explains how to approve it manually, but the provided material does not establish whether or when notarization will be completed. It also does not provide independent security-review results. Users should treat the installation and Accessibility prompts as part of their decision and consult the project’s current instructions before proceeding.
Updates Will Shape Reliability
Gordic invites users who encounter problems to open a GitHub issue and provide their macOS version, Mac model and whether they are using another display, along with steps to reproduce the problem. That information may help the developer address compatibility issues as the project develops.
The GitHub repository lists ways to contribute, including running tests, rendering the sweater catalogue and benchmarking the renderer. The project does not announce a release schedule or a date for Apple notarization. For now, users can check the repository’s releases and documentation for updates, installation guidance and any changes to supported systems.
Key Questions
What does Window Sweaters do?
It adds knitted-style borders to Mac application windows. Users can change the pattern, colors, border width and stitch size from a menu-bar control.
Which Macs and macOS versions does it support?
The project says it is built for macOS 13 or later on Apple Silicon and Intel Macs. The developer reports more hands-on testing on Apple Silicon with macOS 26 than on older systems or Intel machines.
Is Window Sweaters notarized by Apple?
No. The project’s installation instructions say the app is not yet notarized and explain how macOS users can approve it through Privacy & Security if the operating system blocks it.
Does it work with every app?
The developer lists 37 apps with custom colorways. Other apps can receive patterns based on colors sampled from their icons, while apps with no usable icon color receive a stable color based on their name.
Can users turn the borders off for specific apps?
Yes. The project says users can untick an app in the Apps controls to remove its border, or turn the effect off for all apps and enable it only for selected ones.
Source: github.com
