A focused, native macOS utility for resizing and positioning windows with reusable presets and global shortcuts.
Arson keeps window management simple: focus a window, trigger a preset, and continue working. Presets can change width and height independently, align a window, apply offsets, and run from the menu bar or a global keyboard shortcut.
- Reusable window presets — Create, duplicate, reorder, enable, and edit named layouts.
- Flexible sizing — Keep a dimension unchanged or set it in points or as a percentage of the visible screen area.
- Practical positioning — Preserve the current position, center the window, or align it to the left or right edge.
- Global shortcuts — Apply presets without bringing Arson to the foreground.
- Full-screen safety — Shortcuts are suspended while the focused app is in full screen, allowing that app to handle the same keys without an Arson warning.
- Native menu bar workflow — The flame is the default menu bar symbol; alternative symbols and a fully hidden mode are available.
- Background operation — Closing the main window keeps presets and shortcuts available. Arson can also start at login.
- Private by design — Window data stays on the Mac. Arson has no analytics or telemetry; only the optional update check contacts GitHub.
- Authenticated updates — Sparkle verifies update archives and feeds with Arson's EdDSA key; this is separate from Apple Developer ID signing and notarization.
| Main Window | Menu Bar |
|---|---|
 |
 |
- Open the GitHub Releases page.
- Download the latest Arson DMG, open it, and drag
Arson.apptoApplications. - Open Arson and complete the introduction.
- Grant access under System Settings → Privacy & Security → Device Control & Data Access. On older macOS versions, the setting is named Accessibility.
Important
The current release is not signed with an Apple Developer ID or notarized. macOS may block its first launch until it is explicitly approved under System Settings → Privacy & Security → Open Anyway. Only approve a download you trust; see Apple's guidance.
Requirements:
- macOS 26 or later
- Xcode 26.5 or later
- Git
git clone https://github.com/lukas-hzb/arson.git
cd arson
./Scripts/install-local.shThe installer builds the current checkout and maintains one canonical development copy at /Applications/Arson.app. See the development guide for Xcode setup, installer options, permissions, architecture, and tests.
- Focus the window you want to change.
- Choose a preset from Arson, the menu bar, or its assigned global shortcut.
- Use the preset editor to combine independent width, height, position, and offset settings.
- Use Arson → Check for Updates… or the matching menu bar item to check the configured release feed.
Fresh configurations include four starter presets:
| Preset | Shortcut | Behavior |
|---|---|---|
| Compact | ⌃⌘↩ |
Resizes to 80% × 80% and centers the window. |
| Left Half | ⌃⌘← |
Uses the left half of the visible work area. |
| Right Half | ⌃⌘→ |
Uses the right half of the visible work area. |
| Down and Right | ⌃⌘⌫ |
Moves the current window 20 points right and down. |
Existing saved presets are never replaced by starter presets. Full-screen, non-resizable, and Arson-owned windows are left unchanged.
The repository separates product code, tests, release tooling, and longer-form documentation:
Arson/
├── Arson/ App, models, services, views, and resources
├── ArsonTests/ Unit tests
├── ArsonUITests/ UI and accessibility tests
├── Scripts/ Local installation and release utilities
├── docs/ Development, release, and screenshot documentation
└── .github/ CI and contribution templates
| Layer | Technology |
|---|---|
| Language | Swift 6 |
| Interface | SwiftUI and AppKit |
| Window control | macOS Accessibility APIs |
| Global shortcuts | Carbon hot keys |
| Login item | Service Management |
| Updates | Sparkle 2 |
| Tests | Swift Testing and XCTest |
| Automation | GitHub Actions |
Arson is built with Apple's Swift, SwiftUI, AppKit, Accessibility, Carbon, and Service Management technologies.
- Sparkle provides the update framework under its own license.
- Third-party notices distributed with the app are stored in
Arson/Resources/ThirdPartyLicenses.
Bug reports and focused feature proposals are welcome. Code contributions and public forks require prior written authorization because Arson is proprietary source-available software. See CONTRIBUTING.md for known limitations, the contribution process, and contribution terms. Report vulnerabilities according to SECURITY.md.
Development and test commands live in docs/DEVELOPMENT.md; release-only commands live in docs/RELEASING.md.
This project is proprietary source-available software protected by copyright law. Private, personal, educational, and informational use is permitted under the conditions in LICENSE; redistribution and commercial use require prior written permission.
Persona Non Grata: Daniel Harzbecker is expressly excluded from any license or permission to access or use Arson. Third-party components remain subject to their respective licenses.
Copyright (c) 2026 Lukas Harzbecker. All rights reserved.