Rounder

A tiny menu-bar app that beautifully rounds the corners of your macOS screen.

Rounder gives modern rounded corners to older MacBooks and external monitors that still have sharp rectangular edges. It runs quietly in the menu bar, needs no Accessibility or Screen Recording permission, and applies every change instantly, with no restart.

日本語版READMEはこちら

Note: On Macs with a notch, the built-in display already has physically rounded corners, so this app has no visible effect there. It's most useful on external displays and older Macs.

At a Glance

• Best for external monitors that still have sharp rectangular corners
• No invasive permissions: no Accessibility, Screen Recording, Automation, or network access
• Live apply: radius, color, monitor selection, presets, and gaming glow update without restarting the app
• Small surface area: local settings in UserDefaults, menu-bar-only UI, open-source Swift code

Download

Download the latest build from Releases.

• Rounder.zip — the app

Rounder is currently distributed as an unsigned app. If macOS blocks the first launch, right-click Rounder.app, choose Open, then Open again. See FAQ for details.

Why Rounder?

• Works without special macOS permissions
• Covers external monitors and multi-display setups
• Live settings with no app restart
• Per-corner and per-display control
• Presets for switching between subtle, all-corner, and gaming-style setups

Features

• Instant apply — every change takes effect live; no restart, no flicker
• Runs in the menu bar — quiet background utility, no Dock icon
• One-click on/off — toggle the effect straight from the menu bar
• Launch at Login — set it once and forget it (via SMAppService)
• Adjustable radius & color — 0–40 px, any color, with quick black/white/gray swatches
• Corner shape — smooth rounded corners or a sharp polygon cutout
• Per-corner control — enable each of the four corners independently
• Multi-monitor — choose exactly which displays get rounded corners; newly connected displays are covered automatically
• Presets — save, apply, and edit favorite configurations (ships with All / Top / Bottom / Left / Right / None)
• Super Duper Gaming Mode — animated rainbow glow with adjustable speed and intensity
• No special permissions — draws with borderless overlay windows, so no Accessibility / Screen Recording / Automation prompts

System Requirements

• macOS 14.6 (Sonoma) or later
• Apple Silicon or Intel Mac

Installation

Prebuilt App

1. Download Rounder.zip from the latest release and unzip it.
2. Move Rounder.app to your Applications folder.
3. The build is not signed with a paid Developer ID, so on first launch macOS Gatekeeper may block it. Right-click the app → Open → Open, or run:

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

Build from Source

# Open in Xcode
open Rounder.xcodeproj

# …or build from the command line
xcodebuild -project Rounder.xcodeproj -scheme Rounder -configuration Release build

Usage

First Launch

A short setup appears: Welcome → basic settings (radius & color) → done. Choose whether to launch at login, click Start Rounder, and it moves into the menu bar. No permission prompts.

Everyday Use

• Menu bar icon → toggle rounded corners on/off, open Settings, or Quit.
• Settings → adjust radius (0–40 px), color, corner shape, which corners show, which monitors are covered, and Launch at Login. Changes apply the moment you click Apply / OK — no restart.

Presets

• Apply a saved configuration with one click.
• Save the current settings as a new preset.
• Edit or delete existing presets.
• Ships with All Corners / Top Only / Bottom Only / Left Only / Right Only / None.

Settings Reference

General

• Launch at Login — start Rounder automatically when you log in
• Enable rounded corners — master on/off (also available from the menu bar)

Appearance

• Corner radius — 0–40 px
• Corner color — color picker + quick swatches
• Corner shape — rounded corner or polygon cutout
• Corner visibility — toggle each corner independently (2×2 grid)

Monitors

• Monitor selection — pick which displays get rounded corners (stored separately from presets)
• Refresh — re-scan connected displays

Super Duper Gaming Mode

• Rainbow animation with speed (0.1×–5.0×) and glow intensity controls

Technical Notes

• SwiftUI + AppKit, drawing with Core Graphics into borderless NSWindows at .screenSaver level.
• Overlays are rebuilt through a single configuration path, so live apply, presets, the menu toggle, and display hot-plug all share the same reliable code.
• Settings persist in UserDefaults; Launch at Login uses SMAppService.

Releases / CI

Pushing a vX.Y.Z tag triggers a GitHub Actions workflow (.github/workflows/release.yml) that builds the app and publishes Rounder.zip to Releases automatically.

Project Docs

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

Troubleshooting

Rounded corners aren't visible On a Mac with a notch, the built-in display is already rounded — try an external monitor, and make sure the effect is enabled (menu bar → toggle) and the display is selected in Settings → Monitors.

A change didn't seem to apply It should apply instantly; if a display was just connected, open Settings → Monitors → Refresh, or toggle the effect off/on from the menu bar.

No menu bar icon Make sure Rounder is running (it has no Dock icon by design).