Free split screen app for Mac: what to check before you download

A search for a free split screen download on a Mac returns two kinds of result. Download portals that rewrap installers for a handful of apps, and the apps themselves. The portals rank well and add nothing, and in a category where almost every serious option is free anyway, going through one is a risk taken for no gain.

There is also a step most of those pages skip. Recent versions of macOS tile windows without any app at all, and checking that first decides whether anything needs downloading.

Check what is already installed

macOS Sequoia 15 added window tiling to the system, and it is in every release since. Four routes reach the same layouts.

Dragging a window to the left edge, the right edge or a corner snaps it into that region. Holding Option while dragging snaps faster. Holding the pointer over the green button shows layouts under Move and Resize for the active window and under Fill and Arrange for several windows at once. The Window menu in the menu bar carries the same entries, with the layouts grouped under Halves, Quarters and Arrange.

Keyboard shortcuts come with it. Fn-Control-Left Arrow and Fn-Control-Right Arrow send the active window to a half, Fn-Control-F fills the desktop, Fn-Control-R returns a window to the size it had before tiling, and Fn-Control-Shift-Left Arrow arranges two windows in one keystroke.

On macOS Sonoma 14 and earlier none of this exists. The only built-in option there is Split View, reached by holding the pointer over the green button and choosing Full Screen, then Left of Screen or Right of Screen, which puts the two apps in a space of their own with the menu bar and Dock hidden. Anyone on an older release has a genuine reason to install something.

Spend ten minutes with the native layouts before downloading anything. The gap that remains is what to shop for, and it is usually narrower than expected.

What the gap usually turns out to be

Three complaints survive the native features, and they are worth naming because they decide which free app fits.

Thirds are missing. macOS offers halves and quarters and nothing between them, so a two-thirds and one-third arrangement, which is the natural layout on a wide display, cannot be produced at all. Arbitrary sizes are missing for the same reason, since tiling snaps to fixed regions.

Saved arrangements are missing. Nothing in macOS restores a remembered set of window positions when an external display is reconnected, which is the recurring cost on a laptop that docks and undocks.

Automatic placement is missing. macOS tiles on request, one action at a time, and never rearranges existing windows when a new one opens.

The free options, by what they are

Tool	Licence	Requires	Fits
macOS window tiling	Built in	macOS Sequoia 15 or later	Halves and quarters on request
Rectangle	Free and open source	macOS 10.15 or later, Intel and Apple silicon	Shortcuts and snap areas, thirds, repeat a shortcut to cycle sizes
Loop	Free and open source, GPL 3.0	macOS 13 or later	A radial picker driven from one held key combination
Amethyst	Free and open source, MIT	macOS 10.15 or later	Automatic tiling in the style of xmonad
AeroSpace	Free and open source, MIT	See the project page for current requirements	Automatic tiling modelled on i3, with its own virtual workspaces

Rectangle is the default recommendation for a reason. It covers the ordinary gap, it runs on releases going back to macOS 10.15, and repeating the same shortcut cycles through widths, so one combination replaces a memorised list. A paid Rectangle Pro exists with a ten day trial, and the free version is not a crippled demo of it.

Loop takes a different approach. Holding a chosen key brings up a picker around the pointer, and releasing it places the window. It suits people who dislike memorising combinations and requires macOS 13 or later.

Amethyst and AeroSpace are a change of working style rather than a utility. Every window is placed automatically, nothing overlaps, and the layout shifts as windows open and close. Both are MIT licensed. AeroSpace states that it works through the public accessibility interface and will never require System Integrity Protection to be disabled, which is the point to check on a managed or employer-owned machine, since some automatic tilers do ask for that.

Where the download should come from

Every app above is distributed by its own developer, either from the project page or from a code repository. Some also appear on the Mac App Store.

Download portals are a layer on top of that, and the layer is the problem. An installer fetched from a portal may be a wrapper around the real one, may be an older build, and may arrive with its own bundled extras. Nothing is gained, because the original is free and one click away.

The Mac App Store is the other safe route, with a trade-off attached. Store builds run sandboxed, which limits what an app can reach, so a window tool bought there sometimes offers less than the same developer's direct download. Checking which version is being described in a review avoids a surprise.

Two checks take seconds. The first is the source: the developer's own site, the project repository or the App Store, and nothing else. The second is what macOS says when the app first opens. A properly signed and notarized build opens with the ordinary confirmation for a newly downloaded app. A warning that the developer cannot be verified means the build was not notarized, which for a well-known free tool usually means it did not come from the developer.

What these apps ask for once installed

A window manager cannot move another app's windows without permission, so every tool in this category asks for Accessibility access under Privacy and Security in System Settings. Granting it means the app can observe and control other apps' windows, which is exactly what it is for and also the strongest reason to care where the download came from.

Three more things are worth knowing before installing.

Uninstalling is not always a matter of deleting the app. Tools that add a launch item keep running until that item is removed, and the Accessibility permission stays granted until it is revoked by hand in System Settings.

Shortcut collisions are common. A third-party app and the native tiling shortcuts can claim the same combination, and one of them silently loses. Letting the new tool own the arrow-key combinations and leaving Fn-Control-F and Fn-Control-R to macOS avoids most of it.

Two automatic tilers cannot coexist, and an automatic tiler alongside a shortcut-driven snapper produces constant fighting over positions. Pick one model.

How to test one in ten minutes

Installing is easy and judging is not, so it helps to have a short list of things to try before the novelty wears off. Each of these is a place where free tools in this category differ from one another.

Start with the widest layout actually needed. Not halves, which everything does, but the specific arrangement the working day requires: two-thirds and one-third, or a wide main window with two stacked beside it. If the tool cannot produce that in one action, it has not solved the problem that prompted the download.

Then unplug the external display and plug it back in. Windows will pile onto the built-in screen. Whether anything restores them, and whether the tool notices the display change at all, separates a snapper from a layout manager. Most free tools do not restore arrangements, and knowing that on day one prevents a month of disappointment.

Try it on the most awkward app in the workflow next. Apps with a minimum window width will refuse to shrink into a third of a laptop screen, and the tool will place them anyway, leaving a window that overlaps its neighbour. Remote desktop clients and virtual machine windows are the other habitual refusers, since they pass keyboard combinations straight through to the guest system.

Check what happens with a full screen app on screen. Tiling and full screen are different worlds in macOS, and a tool that works perfectly on the desktop may do nothing at all while a full screen app is in front.

Finally, leave the Mac to sleep and come back to it. A window tool that stops responding after sleep, or that has to be quit and relaunched, is a daily annoyance rather than a one-off bug, and it shows up within a day or two of installing.

The setting to check before blaming the app

One native setting causes behaviour that gets attributed to whatever was installed most recently. Under Desktop and Dock, then Mission Control, the option for displays to have separate spaces governs whether each screen keeps its own spaces and menu bar. With it turned off, full screen and Split View take over both displays at once, and window positions on the second screen behave unpredictably.

A second switch sits in the window tiling settings, where edge dragging and Option dragging can each be turned off. A Mac where dragging a window to the edge does nothing may simply have the feature disabled, which is worth ruling out before concluding that macOS cannot tile.

The case none of them cover

There is a version of this problem that no window tool touches, and it is worth recognising before installing a third one in search of a fix.

The two things that need to be visible are both web apps, and both live as tabs in one browser. A layout tool arranges windows, and a tab is not a window. Dragging a tab into a second window makes it placeable, but the two windows share one browser session, so the same service signed in to two accounts cannot be shown twice. Signing in to the second signs out of the first.

The arrangement also decays through the day, because browser windows collect tabs. A half of the screen reserved for the calendar shows something else an hour later, and no amount of snapping keeps a tab in place.

What fixes it is structural: each service gets its own window and its own session container, so the left half of the screen holds the same service all day and a second account is a separate place rather than a sign-out. The workspaces model exists for that, and the supported apps list is the fastest way to check the services involved.

What to change first

Try the native layouts for a week, then install exactly one free tool for the gap that remains: Rectangle for thirds and custom sizes, an automatic tiler if windows should be placed without asking. Download it from the developer rather than a portal, and grant Accessibility access only to something fetched from there. If the pair that will not sit side by side is two web apps in one browser, the tool to test is a browser that keeps each service separate, such as SpaceDeck.