Rounder

A native macOS utility that gives sharp display corners a cleaner, rounded look.

Rounder is especially useful for external monitors and older Macs whose displays still have sharp rectangular corners. It normally stays accessible from the menu bar, but you can hide the icon and keep Rounder running quietly in the background. It requires no Accessibility, Screen Recording, Automation, or network permission.

日本語版 README

Highlights

• Three corner shapes — Rounded, Squircle, and Polygon
• 0–40 px radius with live menu-bar adjustment
• Any corner color plus black / white / gray quick swatches
• Per-corner control for all four corners
• Multi-display selection for choosing which screens Rounder affects
• Presets for saving and applying favorite configurations
• Super Duper Gaming Mode with animated rainbow glow, speed, intensity, and bloom controls
• Launch at Login through SMAppService
• Show or hide the menu-bar icon — Rounder keeps running even while the icon is hidden
• No permanent Dock icon — it only appears while onboarding or Settings is open
• No invasive permissions — local overlay windows and local UserDefaults only

Menu-bar controls

When the menu-bar icon is visible, most everyday controls live directly in the panel: enable/disable, radius, corner shape, quick colors, individual corners, Gaming Mode, Settings, and Quit.

Radius and shape changes update the existing overlay windows in place, so you can drag and compare shapes without repeatedly rebuilding the overlay.

On notch-equipped Macs, the built-in display already has physically rounded corners. Rounder is most noticeable on external displays and older Macs.

Download & install

Download Rounder.zip from Releases, unzip it, and move Rounder.app to /Applications.

Release builds are ad-hoc signed, but not Developer ID signed or notarized. Because of that, macOS Gatekeeper may block the first launch. If it does:

1. Right-click Rounder.app and choose Open.
2. Choose Open again in the confirmation dialog.

If necessary, you can also remove the quarantine attribute manually:

xattr -dr com.apple.quarantine /Applications/Rounder.app

See the FAQ for more details.

First launch

Rounder shows a short onboarding flow:

Welcome → basic radius/color setup → finish

Choose whether Rounder should launch at login, then click Start Rounder. It starts running in the background, and you can later choose whether the menu-bar icon should remain visible.

Settings

The menu panel is for fast adjustments. The full Settings window provides:

• full color picker
• display selection
• preset management
• Gaming Mode speed / intensity / bloom width
• Launch at Login
• menu-bar icon visibility
• detailed corner configuration

If the menu-bar icon is hidden, open Rounder.app again to show Settings. The icon stays hidden until you explicitly enable it again, and automatic login launches remain silent.

Requirements

• macOS 14.6 or later
• Apple Silicon or Intel Mac

Privacy & permissions

Rounder does not request Accessibility, Screen Recording, Automation, Contacts, Location, Microphone, Camera, or network permissions. Settings stay on your Mac in UserDefaults.

See Privacy and Security.

Technical notes

• SwiftUI + AppKit
• borderless NSWindow overlays at .screenSaver level
• Core Graphics / Core Animation corner rendering
• a real NSMenu hosts the interactive SwiftUI menu panel, preserving normal macOS menu tracking behavior
• CornerGeometry / ScreenCorner are the shared source of truth for initial placement, live resizing, menu previews, orientation, and Gaming hue mapping
• radius and shape use in-place geometry updates; structural changes still use the full overlay rebuild path

Build from source

open Rounder.xcodeproj

Or from the command line:

xcodebuild -project Rounder.xcodeproj -scheme Rounder -configuration Release build

Releases / CI

Pushing a vX.Y.Z tag runs the release workflow, which checks corner-geometry regressions and required English/Japanese localizations before building and packaging Rounder.zip.

Project docs

• Changelog
• FAQ
• Privacy
• Security
• Contributing
• Demo asset checklist
• Launch checklist
• License

Troubleshooting

Rounded corners are not visible
Make sure Rounder is enabled and the target display is selected in Settings. On notch-equipped Macs, try an external display because the built-in panel is already physically rounded.

A change did not seem to apply
Radius and shape should react immediately in the menu panel. For display-selection or other structural changes, toggle Rounder off/on or refresh the display list in Settings.

Want the menu-bar icon back?
Open Rounder.app to show Settings, then enable Show menu bar icon. Rounder keeps running even while the icon is hidden.