CurveFan

Native macOS fan speed monitor and controller for Apple Silicon

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CurveFan sits in your menu bar and gives you direct control over fan speed through the SMC on Apple Silicon Macs. A privileged LaunchDaemon handles all hardware writes; the UI process stays unprivileged. macOS automatic fan control is always restored when you quit or select System Auto.

Warning — CurveFan writes directly to SMC fan registers. Manual fan control carries thermal risk. Use with care.

Tech Stack

Layer	Technology
Language	Swift 6.4 (strict concurrency)
UI	SwiftUI + AppKit (NSStatusItem / NSPanel)
Charts	Swift Charts — RPM trend, fan curve preview
Hardware	IOKit AppleSMC — helper-side only
IPC	Unix socket · JSON · 4-byte length-prefixed framing
Build	Swift Package Manager
Tests	XCTest · no hardware required

Features

• Menu bar panel — live RPM gauge, CPU/GPU temperatures, fan range
• System Auto — one click restores macOS native fan control
• Fan curve presets — Quiet, Balanced, MaxCool with real-time SMC writes
• Manual RPM — fixed target with hardware bounds clamping
• Batch SMC reads — all temperature keys fetched in a single IPC round trip
• Wake-event recovery — re-applies manual settings after system sleep
• Apple Silicon M1–M5 — generation-aware SMC key database and unlock sequences

Architecture

CurveFanCore (library)      ← shared models, IPC types, SMC decoder, presets
    ├── CurveFan (SwiftUI)  ← unprivileged UI process, talks over Unix socket
    └── CurveFanHelper      ← root LaunchDaemon, sole SMC / IOKit contact

The app never touches the SMC directly. Every hardware operation crosses a Unix socket as a length-prefixed JSON command. The helper validates all inputs (key format, fan index, RPM range) before writing.

Requirements

• Apple Silicon Mac (M1 or later) with at least one controllable fan
• macOS 26.0 or newer
• Administrator access (for privileged helper installation on first launch)

Install

Download the latest DMG from Releases.

1. Open the DMG and drag CurveFan.app to your Applications folder.
2. Double-click CurveFan.app.
3. On first launch, CurveFan will ask to install its privileged helper — click Install Helper and enter your password.
4. Done. The helper starts automatically at login from this point on.

If macOS says the app is damaged or can't be opened:

sudo xattr -cr /Applications/CurveFan.app

Build from Source

git clone git@github.com:BeastOrange/CurveFan.git && cd CurveFan

swift build                   # debug build, all targets
swift test                    # unit tests (no hardware required)
bash build_app.sh release     # bundle .build/release/CurveFan.app
bash build_dmg.sh 1.0.0       # package CurveFan-1.0.0.dmg
sudo bash setup.sh            # install directly without DMG
bash setup.sh --check         # verify installation status

Smoke tests

bash smoke_ipc_local.sh    # full IPC round-trip with fake SMC, no hardware
bash smoke_hardware.sh     # live SMC reads (helper must be running)

Uninstall

sudo bash uninstall.sh              # remove app, helper, daemon, user data
sudo bash uninstall.sh --keep-data  # keep presets

Safety

• Quitting CurveFan or selecting System Auto restores macOS fan control before exit.
• The helper also restores auto control on SIGTERM/SIGINT as a second line of defense.
• RPM values are clamped to the fan's hardware-reported range; out-of-range requests are rejected.
• Report security issues privately — see SECURITY.md.

License

MIT — see LICENSE.