Fan Sooner

A free, open-source macOS menu bar app for monitoring your system and controlling fan speeds. Keep your Mac chilly.

Download the latest release

Screenshots

Features

• Fan Control — Live RPM display in the menu bar with per-fan manual speed sliders
• Performance Mode — Automatic fan curves with Low/Medium/High/Max/Ultra presets (Ultra = pure performance curve, not constant full blast)
• CPU Monitor — Real-time usage graph, top consuming apps, temperature, and uptime
• Memory Monitor — Usage breakdown with donut chart, pressure, swap, and top consumers
• Battery Monitor — Charge gauge, health percentage, cycle count, and temperature
• Disk Monitor — Storage breakdown by category with SSD temperature
• Temperature Sensors — Color-coded readings for CPU, GPU, memory, SSD, battery, and more
• Auto-Update — Checks for new releases from GitHub and notifies you in-app
• Apple Silicon and Intel Mac support

Install

Download (recommended)

1. Grab Fan Sooner.dmg from the latest release
2. Open the DMG and drag Fan Sooner into Applications (not Desktop or Downloads)
3. Launch Fan Sooner — it appears in the menu bar
4. On first launch, approve it under System Settings → General → Login Items (Allow in the Background) so the fan-control helper can run
5. Settings → Helper should show Ready before Max / Ultra will change fan speeds

The DMG is signed, notarized, and stapled — Gatekeeper will let it through. Fan writes need that notarized helper; a dragged Debug build will not.

Build from source

Requirements:

• macOS 13.0+
• Xcode 15+
• XcodeGen (brew install xcodegen)

git clone https://github.com/idevtim/chillmac.git
cd chillmac
xcodegen generate
open ChillMac.xcodeproj   # ⌘R for day-to-day UI work

Or:

xcodebuild -project ChillMac.xcodeproj -scheme ChillMac -configuration Debug build

What Debug vs Release is for

Goal	How
Menu bar UI, sensors, Native Cool	Xcode Debug / adhoc Run is fine
Max / Ultra fan control on a real install	Notarized Release app in /Applications (./scripts/build-dmg.sh)

Copying a Debug Fan Sooner.app into /Applications looks installed but the privileged helper usually fails to spawn (EX_CONFIG / launch constraints). Use the release pipeline (or an equivalent Developer ID sign → notarize → staple) and approve Login Items once.

Release / local notarized install

cp .env.example .env   # APPLE_ID, APPLE_APP_SPECIFIC_PASSWORD, APPLE_TEAM_ID
# Optional: APPLE_SIGNING_NAME="Your Name" if not Tim Murphy
brew install create-dmg
./scripts/build-dmg.sh
# Install from build/Fan Sooner.dmg → /Applications, launch, approve Login Items

Helper health check:

launchctl print system/com.idevtim.ChillMac.Helper3 | rg 'state =|pid ='

If Helper stays “Not ready” after an upgrade: use in-app Install Helper, or as a last resort sudo sfltool resetbtm and reboot (resets all third-party Login Items approvals).

How It Works

Two-process architecture with privilege separation:

Menu Bar App (UI + read-only SMC) ──XPC──> Helper Daemon (root, write SMC)

• Main app (unprivileged) — Reads SMC sensors every 2 seconds and displays a SwiftUI popover with system dashboards.
• Helper daemon (root) — Registered via SMAppService from Contents/Library/LaunchDaemons/…Helper3.plist, binary at Contents/Library/HelperTools/. Handles fan speed/mode writes over XPC. Validates the caller's code signature before accepting connections (relaxed in Debug).

On Apple Silicon, the helper manages SMC test mode to bypass thermalmonitord for manual fan control. Signal handlers ensure cleanup if the helper exits unexpectedly. Fans always reset to automatic mode on app launch and quit.

Contributing

Contributions are welcome! Fork the repo, make your changes, and open a PR.

# Fork and clone
git clone https://github.com/YOUR_USERNAME/chillmac.git
cd chillmac

# Set up
brew install xcodegen
xcodegen generate

# Build and run from Xcode, or:
xcodebuild -project ChillMac.xcodeproj -scheme ChillMac build

# Unit tests (Swift Testing)
xcodegen generate && xcodebuild -project ChillMac.xcodeproj -scheme ChillMac -destination 'platform=macOS' test

For Max/Ultra changes, also verify a notarized /Applications install (see Install above). Agents: see AGENTS.md → Getting started.

Project Structure

ChillMac/
  App/              Entry point, status bar controller, settings, update checker
  Views/            SwiftUI views (dashboard, fan controls, detail panels, settings)
  Fan/              Data models and monitoring engines (CPU, memory, battery, disk)
  SMC/              IOKit bridge to Apple SMC driver
  XPC/              Helper connection and installation
FanControlHelper/   Privileged helper daemon (runs as root)
Shared/             XPC protocol shared between app and helper
scripts/            Build and release tooling

License

MIT — see LICENSE for details.