plain corners · a mac utility

the corners are too round. fix them.

macOS Tahoe and Golden Gate rounded every window into a lozenge — and shipped no way to change it. Plain Corners is a tiny native app that puts the window radius back in your hands: pick a number, apply, reopen your apps. No daemon, no admin password, no telemetry, and an undo button for the whole thing.

v0.1.0 preview · mit · macos 26.5+ · universal

the problem

somewhere in the redesign, window corners became semicircles. every window on every mac now ends in a curve you never chose — and system settings, thorough as it is about accent colors and scrollbars, offers exactly nothing for the shape your windows are cut from.

there is no slider. there is no checkbox. the value lives in an undocumented preference, and unless you enjoy typing defaults write incantations into terminal, you live with the rounding.

before · default macosafter · plain corners 4
illustrative comparison; the shipped radius varies by macOS version and app. plain corners accepts 0.1–40 — or hands the value back to macOS.

the fix

plain corners edits two preference keys and quits: NSConvolutionOverride1 for window corners and NSSplitViewItemGlassMinimumCornerRadius for floating sidebars. your apps pick the values up at launch. nothing is injected, patched, or hooked — it's the same two values you could set by hand, with a preview, presets, and a restore point.

The Plain Corners app window: four presets, a radius slider, an illustrative preview, and apply and restore buttons
the whole app: four presets, one slider, one preview. apply, then reopen your apps.
almost square (0.1)barely a suggestion of a corner
classic (4)the pre-redesign look
subtle (10)a hint of curve, nothing more
rounded (20)for the moderates
the slider (0.1 – 40)fine-grained, if you want it

light by design

this is not a subscription, a service, or a menu-bar squatter. it is a small app that does one thing and gets out of the way.

no background processwrites two preferences and exits; nothing lingers after
no injection, no hookingapps read the value natively at next launch; nothing touches other processes
no network, no accountno telemetry, no updater, no sign-in; it never phones home
small on purposea 403 KB binary, under 500 lines of Swift including tests, zero dependencies
an undo buttonthe original values — or their absence — are recorded before the first change; restore previous puts them back

the honest part

the preferences are undocumented. native windows follow them; electron and custom-drawn windows may not; borderless terminals stay square. apple can remove these keys in any macOS update, and nothing here can stop that.

the 0.1.0 release is a working preview — ad-hoc signed rather than notarized, so macOS will ask you to vouch for it once (privacy & security → open anyway). the build is universal, but only apple silicon has been exercised so far. it is honest about being a small tool that does one thing.

get it

plain corners · 0.1.0 preview

macos 26.5+ · universal (arm64 + x86_64) · mit licensed · 456 KB

download ↗source ↗

shasum -a 256 PlainCorners-0.1.0-preview.zip · compare with SHA256SUMS.txt before opening

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