DockDoor is a window manager written in Swift that borrows from Linux
Window peeking, alt-tab and other enhancements for macOS
At a glance
- What is it?
- The GPL v3 Mac utility that brought Window Peeking back to macOS, ships as a signed .dmg through GitHub releases, updates itself with Sparkle, and has a paid sibling that replaces the Dock outright.
- Who is it for?
- DockDoor is a small, opinionated utility that took a feature macOS removed and rebuilt it in a few thousand lines of Swift, which is why it fits in a repository this size. The tree is telling: `DockDoor.xcodeproj`, `Sparkle/`, `DockDoorTests/` and a handful of static HTML pages, with no dependency manifest because there is nothing to depend on beyond Apple's frameworks.
- Can I use it commercially?
- Check first. The repository uses a licence we do not classify automatically, so read its LICENSE file before any commercial use.
- Is it still maintained?
- Yes. The repository last received commits 17 days ago.
- What is it written in?
- Mainly Swift, according to GitHub's language statistics.
Answers come from the project's GitHub data, last synced on September 22, 2026, and from our analysis. They are not legal advice.
Editorial analysis
Window Peeking is the whole pitch
The README is short and the central claim is in the first paragraph: DockDoor reintroduces the missing Window Peeking functionality to macOS, inspired by the utility found in Windows and Linux environments. The diagnosis underneath it is that the native macOS Dock lacks context when multiple windows of the same application are open, which is exactly the situation where a file manager with twelve open folders becomes hard to navigate.
The fix is to let you visualise, manage and switch between open windows simply by hovering over your Dock icons. That is the entire feature, and the README frames it as feeling like a native extension of the operating system rather than a replacement for it. The tag line at the top puts it as effortless Alt+Tab switching and dock previews that respect your privacy.
The privacy part is doing real work in that sentence, though the README does not elaborate on it. What it does say is that DockDoor is built entirely open source under the GNU General Public License v3.0, with the terms in the `LICENSE` file. For an application whose entire job is to enumerate and capture images of every window on your screen, source availability is the argument, and it is a GPL choice that means any derivative has to publish too.
Full documentation lives off the repository at dockdoor.net, which the README links from both the about section and the features section.
The feature list is mostly screenshots, which is fair for a UI tool
The features section is unusual in that nearly every entry is an image rather than a paragraph. Dock Previews, Alt+Tab Switching, Cmd+Tab Enhancements, Dock Preview Layouts, Window Switcher Layouts, Enhanced Previews and Compact List View are all screenshots with a one line label, and then the section ends with another link to dockdoor.net for more.
Two entries do carry text, and they are the two that solve problems you would not guess from a screenshot. Dock Locking is described as locking the Dock to a specific monitor in multi-display setups so it stops jumping between screens. That is a real annoyance for anyone with two displays and a Dock that has no opinion about which one owns it.
Calendar Integration is listed with a screenshot and no explanation at all, which is a fair signal that you will have to try it to understand it. A reasonable guess from the filename is that previews or the switcher surface upcoming events, but nothing in the README confirms it, so it is better left as something to try rather than something to describe.
The Compact List View entry is the other one to try, because a switcher that lists windows as text rather than thumbnails behaves very differently with many windows open, and screenshot documentation cannot tell you how a layout scales.
Free and Pro are two applications from one developer
The README is unusually direct about the commercial arrangement. DockDoor Free has no paywall and never will, and every feature in the repository is free forever. That is a commitment stated in the document rather than inferred from a pricing page.
DockDoor Pro is a separate paid app from the same developer, hosted at pro.dockdoor.net, and the README recommends buying it as the best way to support the free one. The functional difference is not a feature gate on the same binary. Pro replaces the macOS Dock entirely, where Free augments it. The README lists live window previews with more than twenty actions plus a full Alt+Tab replacement, spring magnification at your display's full refresh rate, folder fan-out, a drag-and-drop file tray with AirDrop, and right-click quick actions.
It also lists visual work that Free does not attempt: Liquid Glass, frosted or clear materials, user profiles, and a different Dock on each display. Plus a widget marketplace with clock, weather, battery, now playing and community widgets.
The price is $20 one-time for three Macs, with no subscription and a 14-day money-back guarantee. One-time pricing for three machines is a deliberate signal, and it is worth noting that the feature list for Pro overlaps DockDoor Free on the axis Free is built around, so the upsell is about depth and about replacing the Dock rather than about unlocking the peeking.
A twenty-three entry tree with no dependency manifest
The repository is small in a way that says a lot about the approach. There is no package manager file of any kind, no `Package.swift` and no `Cartfile`. The top level is `DockDoor.xcodeproj/`, `DockDoor/`, `DockDoorTests/`, `Assets/`, `BuildTools/`, `Sparkle/`, `resources/`, `README.md`, `CHANGELOG.md`, `LICENSE`, `AGENTS.md`, `crowdin.yml`, `appcast.xml`, `.swiftformat`, `.release.json` and `.gitignore`.
Absence of a dependency manifest in a Swift macOS app is unusual now, and `Sparkle/` in the tree explains it. Sparkle is the standard update framework, and it is vendored as a directory rather than pulled through Swift Package Manager, which means the update mechanism travels with the checkout instead of being resolved at build time. `appcast.xml` alongside it is the Sparkle feed the app polls for new versions.
`crowdin.yml` is a translation pipeline configuration, and the contributing section links a Crowdin project, so localisation goes through that service rather than through pull requests against the README. The static site files are `index.html`, `docs.html`, `donate.html`, `styles.css` and `scripts.js`, with `CNAME` for a custom domain, which together are a hand written landing page hosted from the repository itself.
`AGENTS.md` at the root is a file aimed at coding agents working in this repository, and `.swiftformat` and `.release.json` are the formatting and release automation configuration. The `BuildTools/` directory holds whatever the build invokes beyond Xcode itself.
Release 1.40.0 shows the feature set, and the beta shows the edges
Three releases are recorded, all within the same week in September 2026, and read together they tell you more about the project than a roadmap would. Version 1.40.0 shipped on 2026-09-03 and is a features release. Its headline is browsing and controlling every window from the menu bar: a new Window Actions submenu listing every open app and window, with actions for minimize, close, quit, and quarter or half placement.
The rest of 1.40.0 is the kind of detail work that separates a utility from a demo. Right-clicking a preview now offers the full action set grouped by Window, Arrange and Application, and windowless apps get that same set rather than only Open New Window and Quit. There is a new keep preview open after hover activation option under Settings > Dock Previews, off by default and only available when hovering is set to bring windows to the front, which is careful conditional design for a setting that could otherwise surprise people.
Version 1.40.1, later the same day, is a single hot fix: clicks were not reacting inside dock windows on macOS 26.3 and above. A same-day patch for an OS point release that broke input handling is a reasonable thing for a project that depends on window server behaviour.
Then there is 1.40.1.0.3, published 2026-09-05 and labelled a beta release warning, an unstable pre-release version intended for testing purposes only. Its two fixes are both about correctness under motion: torn preview thumbnails during Space switches, where a capture taken while you switch desktops produced a cut-off or glitched image and now keeps the last good preview until a clean one is ready, and quit apps lingering in the switcher, where windows belonging to closed apps are now cleared even during an active switcher session.
The four-part version numbering on the beta, appended to the hot fix version, suggests the project builds prereleases as suffixes of a release rather than as a separate track.
Distribution is a .dmg link and a download badge
The top of the README is where you actually install this. Two badges sit at the top: one counting downloads of the latest release and one counting total downloads, both wired to the GitHub releases page, with the total badge using the `hack-the-box` logo as its badge colour, which is a small joke rather than a partnership.
The download itself points straight at a `DockDoor.dmg` asset in the latest release, so there is no installer landing page between the README and the file. For a GPL v3 utility that is the expected arrangement, and it also means the update path is the same artefact: the app checks `appcast.xml` and offers the newer build rather than sending you to a website.
The application is a Swift build with an Xcode badge, and it will need Accessibility permission to do its job, since reading window titles and capturing window images is not something macOS grants to arbitrary applications. That is not stated in the README, but it follows from what the app does, and it is the first permission dialog anyone installing this will meet.
For context on scale, the repository has 6081 stars and 224 forks with 92 open issues, and the last recorded push is 2026-09-20, two weeks after the 1.40.0 release line. The homepage is dockdoor.net, and the download badge on the releases page is the better route to a current build than building from Xcode.
Editorial conclusion
DockDoor is a small, opinionated utility that took a feature macOS removed and rebuilt it in a few thousand lines of Swift, which is why it fits in a repository this size. The tree is telling: `DockDoor.xcodeproj`, `Sparkle/`, `DockDoorTests/` and a handful of static HTML pages, with no dependency manifest because there is nothing to depend on beyond Apple's frameworks. If Window Peeking is the thing you missed, the free app has it and the README commits to it staying free. If you want the Dock itself replaced rather than supplemented, that is DockDoor Pro, a separate $20 purchase for three Macs with no subscription. Install from the releases page rather than building it, since the update feed is what keeps an Accessibility-permission app current.
Frequently asked questions
What is DockDoor?
It is a macOS utility that reintroduces Window Peeking, the feature Windows and Linux desktops have and macOS dropped. Hovering over a Dock icon shows previews of every open window for that app, so you can pick the right one instead of cycling through Cmd+Tab. The README also lists Alt+Tab switching, Cmd+Tab enhancements, Dock locking for multi-display setups, a compact list view and calendar integration.
Is DockDoor worth it?
DockDoor Free has no paywall, the README states it never will, and every feature in the repository is free forever. It is worth it if what you want is window previews back, since that is the core feature and it is not held back. DockDoor Pro is a separate $20 one-time purchase for three Macs that replaces the Dock entirely and adds a full Alt+Tab replacement, spring magnification, folder fan-out and a widget marketplace, and the README recommends buying it as the best way to support the free app.
How safe is DockDoor?
The README describes it as built entirely open source under the GNU General Public License v3.0, with the terms in the LICENSE file, and the tagline says dock previews respect your privacy. Because the project is source available under the GPL, the behaviour that captures window images can be read rather than trusted. You will still be granting Accessibility permission, since enumerating window titles and capturing previews is not something macOS grants to arbitrary applications.
Official sources
Add this badge to your README
If you maintain this project, the badge below links readers to this analysis and shows its maintenance status from the daily GitHub snapshot. Paste the markdown into your README; add ?metric=license or ?metric=stars to the image URL for a different field.
[](https://hysenlabs.com/projects/ejbills-dockdoor)