System Monitor for macOS

A professional-grade, feature-rich system monitoring app for macOS 14+

Built with pure Swift & SwiftUI | Open Source | Production Ready

Created by Ersin KOC | @ersinkoc

Features • Installation • Build • Usage • License

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✨ Features

📊 CPU Monitoring

• Real-time overall CPU usage (%)
• Per-core usage breakdown (P-cores & E-cores on Apple Silicon)
• User/System/Idle time breakdown
• CPU frequency monitoring (MHz)
• Thermal state tracking (Nominal/Fair/Serious/Critical)
• 5-minute historical chart with smooth animations

🎮 GPU Monitoring

• GPU usage percentage
• Apple Silicon specific: Device/Renderer/Tiler utilization breakdown
• GPU memory tracking (allocated & in-use)
• GPU name/model detection via Metal API
• Architecture detection (Apple Silicon vs Intel)
• Historical usage chart

💾 Memory Monitoring

• Active, Inactive, Wired, Compressed memory breakdown
• Memory pressure indicator (Normal/Warning/Critical)
• Swap usage tracking
• Visual memory breakdown bar with color coding
• 5-minute historical chart
• Real-time percentage display

💿 Disk Monitoring

• Total, used, free space (GB/TB)
• Usage percentage with color coding (Green/Orange/Red)
• Real-time read/write speeds (MB/s, GB/s)
• Dual I/O charts (separate read/write history)
• Total bytes read/written since boot
• Visual space breakdown bar
• Mount point information

🌐 Network Monitoring

• Real-time upload/download speeds
• Dual charts (separate upload/download history)
• Total bytes transferred (in/out)
• Peak speed indicators
• Auto-formatted speeds (B/s → KB/s → MB/s → GB/s)
• Active interface detection (WiFi/Ethernet)

🌡️ Sensors & Fans (Advanced)

• CPU/GPU/System temperatures via SMC (System Management Controller)
• Fan speed monitoring with RPM display
• Manual fan control with safety warnings ⚠️
• System power consumption (Watts)
• Temperature status (Cool/Warm/Hot/Critical)
• Color-coded temperature gauges
• Auto-restore fans to automatic mode on quit
• Emergency "Reset All to Auto" button

⚙️ Settings & Customization

• General Settings:
  • Customizable update interval (0.5-5 seconds)
  • Launch at login option
  • Show/hide in Dock
• Menu Bar Settings:
  • Toggle CPU/Memory/Network display
  • Icon style selection (Percentage/Icon/Graph)
• Alert Settings:
  • CPU usage threshold (50-100%)
  • Memory usage threshold (70-100%)
  • Temperature threshold (70-100°C)
  • macOS native notifications
  • 5-minute cooldown between same alerts

📤 Data Export

• Export all metrics to CSV format
• Timestamped data for analysis
• Includes: CPU, GPU, Memory, Disk I/O, Network
• NSSavePanel integration
• Auto-open exported file in Finder

🎯 Menu Bar Integration

• Live CPU percentage display (updates every second)
• Settings-based customization
• Always accessible from menu bar
• Click to open detailed popover (6 tabs)
• Low system resource usage (<5% CPU idle)

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🎯 Why SystemMonitor?

Feature	iStat Menus	Stats	SystemMonitor
CPU Monitoring	✅	✅	✅
GPU Monitoring	✅	✅	✅
Memory	✅	✅	✅
Disk I/O	✅	✅	✅
Network	✅	✅	✅
Sensors	✅	✅	✅
Fan Control	✅	❌	✅
Notifications	✅	❌	✅
CSV Export	✅	❌	✅
Settings Window	✅	⚠️	✅
Open Source	❌	✅	✅
Modern SwiftUI	❌	✅	✅
Price	$11.99	Free	Free

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📦 Installation

Option 1: Build from Source (Recommended)

See BUILD.md for detailed instructions.

Quick Start:

1. Clone repository
2. Open in Xcode 15+
3. Disable App Sandbox (Signing & Capabilities)
4. Build & Run (⌘R)
5. Look for gauge icon in menu bar

Option 2: Swift Package Manager

cd SystemMonitor
swift build -c release
.build/release/SystemMonitor

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🚀 Usage

Getting Started

1. Launch App: Click menu bar icon (gauge symbol)
2. Navigate Tabs: Use segmented picker to switch between metrics
3. View Details: Each tab shows real-time data + 5-minute history
4. Settings: Click "Settings" button in footer
5. Export Data: Click "Export" button → Save as CSV

Tab Overview

CPU Tab 📊

• Large percentage display with color coding
• Per-core usage bars (if available)
• User/System/Idle breakdown
• Frequency, core count, architecture info
• 5-minute usage history chart

GPU Tab 🎮

• GPU usage percentage with progress ring
• Utilization breakdown (Apple Silicon: Device/Renderer/Tiler)
• GPU memory usage
• Model information
• 5-minute usage history chart

Memory Tab 💾

• Usage percentage with progress ring
• Active/Wired/Compressed/Inactive breakdown
• Visual memory bar (color-coded)
• Swap usage (if applicable)
• 5-minute usage history chart

Disk Tab 💿

• Space usage with progress ring
• Read/write speeds (MB/s)
• Dual I/O history charts
• Total data transferred
• Mount point info

Network Tab 🌐

• Upload/download speeds (formatted)
• Dual speed history charts
• Total bytes in/out
• Peak speed indicators

Sensors Tab 🌡️

• Temperature gauges (CPU/GPU/System)
• Temperature status indicator
• Power consumption (Watts)
• Fan speed monitoring
• Manual fan control (Advanced users only!)
• Safety warnings

Settings Configuration

General Settings:

• Update Interval: 0.5-5 seconds (default: 1s)
  • Lower = More responsive, higher CPU usage
  • Higher = Less responsive, lower CPU usage
• Launch at Login: Auto-start with macOS
• Show in Dock: Display app icon (requires restart)

Menu Bar Settings:

• Show CPU/Memory/Network: Toggle what's displayed
• Icon Style: Percentage (75%) / Icon Only / Graph

Alert Settings:

• Enable Alerts: Toggle notification system
• CPU Threshold: 50-100% (default: 80%)
• Memory Threshold: 70-100% (default: 90%)
• Temperature Threshold: 70-100°C (default: 85°C)
• Alerts have 5-minute cooldown to avoid spam

Data Export

1. Click "Export" button in popover footer
2. Choose save location
3. File format: CSV with headers
4. Columns: Timestamp, CPU, GPU, Memory, Disk R/W, Network Up/Down
5. Auto-opens in Finder after save

Fan Control ⚠️

WARNING: Manual fan control can damage hardware if used incorrectly!

How to use:

1. Go to Sensors tab
2. Toggle "Manual" switch for a fan
3. Read and accept warning dialog
4. Adjust slider to set target RPM
5. Monitor temperatures carefully
6. Click "Reset All to Auto" or quit app to restore automatic control

Safety Features:

• Warning dialog before enabling manual mode
• Persistent warning banner
• Emergency reset button
• Auto-restore on app quit
• All fans restored to automatic mode on quit

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🏗️ Architecture

Technical Stack

• Language: Swift 5.9+
• UI Framework: SwiftUI + AppKit hybrid
• Concurrency: Swift Concurrency (async/await, actors)
• Platform: macOS 14.0+ (Sonoma)
• APIs: IOKit, SMC, Metal, UserNotifications, FileManager

Project Structure

SystemMonitor/ (40 Swift files, 4,448 lines)
├── App/
│   ├── SystemMonitorApp.swift          # @main entry point
│   ├── AppDelegate.swift                # Menu bar setup, lifecycle
│   └── Info.plist                       # LSUIElement config
├── Core/
│   ├── Managers/
│   │   ├── MenuBarManager.swift         # NSStatusItem + popover
│   │   └── MonitoringManager.swift      # Central coordinator (6 actors)
│   ├── Services/ (6 Actors)
│   │   ├── CPUMonitor.swift             # CPU metrics
│   │   ├── GPUMonitor.swift             # GPU metrics
│   │   ├── MemoryMonitor.swift          # Memory metrics
│   │   ├── DiskMonitor.swift            # Disk metrics
│   │   ├── NetworkMonitor.swift         # Network metrics
│   │   ├── SensorMonitor.swift          # Temperature/Fan/Power
│   │   └── FanController.swift          # Manual fan control
│   ├── SystemAPIs/
│   │   ├── IOKitBridge.swift            # IOKit C API wrapper
│   │   ├── SMCBridge.swift              # SMC (undocumented API)
│   │   └── SysctlHelper.swift           # sysctl wrapper
│   └── Utils/
│       ├── NotificationManager.swift    # Alert system
│       ├── DataExporter.swift           # CSV export
│       ├── DataFormatter.swift          # Byte/speed formatting
│       └── Logger.swift                 # Logging utility
├── Models/ (11 Models)
│   ├── SystemMetrics.swift              # Main container
│   ├── CPUMetrics.swift                 # CPU data
│   ├── GPUMetrics.swift                 # GPU data
│   ├── MemoryMetrics.swift              # Memory data
│   ├── DiskMetrics.swift                # Disk data
│   ├── NetworkMetrics.swift             # Network data
│   ├── SensorMetrics.swift              # Sensor data
│   ├── AppSettings.swift                # @AppStorage settings
│   ├── HistoricalData.swift             # Time-series manager
│   └── CircularBuffer.swift             # FIFO buffer
└── Views/
    ├── Popover/ (6 Metric Views)
    │   ├── PopoverContentView.swift     # Main container + tabs
    │   ├── CPUView.swift
    │   ├── GPUView.swift
    │   ├── MemoryView.swift
    │   ├── DiskView.swift
    │   ├── NetworkView.swift
    │   └── SensorView.swift
    ├── Components/ (Reusable)
    │   ├── LineChartView.swift          # Time-series chart
    │   ├── ProgressRingView.swift       # Circular progress
    │   ├── MetricRowView.swift          # Label + value row
    │   └── FanSliderView.swift          # Fan control slider
    └── Settings/ (3 Settings Views)
        ├── SettingsWindow.swift         # TabView container
        ├── GeneralSettingsView.swift
        ├── MenuBarSettingsView.swift
        └── AlertSettingsView.swift

Key Design Patterns

Actor-based Concurrency:

• Each monitor is an actor for thread safety
• Prevents data races
• Swift Concurrency best practices

Parallel Data Collection:

await withTaskGroup { group in
    group.addTask { CPU }
    group.addTask { GPU }
    group.addTask { Memory }
    group.addTask { Disk }
    group.addTask { Network }
    group.addTask { Sensors }
}

Memory-Efficient Storage:

• Circular buffer (300 points = 5 min @ 1 sec)
• Fixed memory footprint
• No memory growth over time

Smart Equality:

// Only update if change > threshold
static func == (lhs: CPUMetrics, rhs: CPUMetrics) -> Bool {
    abs(lhs.usage - rhs.usage) < 1.0 // <1% change
}

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⚠️ Known Issues & Limitations

SMC & Sandbox

• Temperature/Fan features require App Sandbox disabled
• Development: Signing & Capabilities → Remove App Sandbox
• Production: Requires proper entitlements (see BUILD.md)
• Alternative: Run without sandbox restrictions

Hardware Compatibility

• SMC keys vary by hardware:
  • M1/M2/M3/M4 use different keys
  • Intel Macs use different keys
  • Some sensors may not be available
• Fan control:
  • Experimental feature
  • May not work on all Macs
  • Use with extreme caution

Permissions

• UserNotifications: Prompt on first alert
• IOKit: Requires elevated access for some features
• SMC: Requires sandbox disabled

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🛠️ Building from Source

See BUILD.md for comprehensive build instructions.

Quick Build:

# Clone repository
git clone https://github.com/ersinkoc/SystemMonitor.git
cd SystemMonitor

# Open in Xcode
open SystemMonitor.xcodeproj

# Or build with SPM
swift build -c release

Requirements:

• macOS 14.0+ (Sonoma)
• Xcode 15.0+
• Swift 5.9+

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📄 License

MIT License - See LICENSE file for details.

Copyright (c) 2026 Ersin KOC

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🙏 Credits

Created by:

• Ersin KOC - @ersinkoc | GitHub

Inspired by:

• iStat Menus - Industry standard
• Stats - Open source alternative
• eul - SwiftUI monitor

SMC Research:

• apple_sensors
• Open source SMC implementations

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📞 Support

• Repository: github.com/ersinkoc/SystemMonitor
• Issues: Report a bug
• Discussions: Ask a question
• Author: Ersin KOC | @ersinkoc

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Built with ❤️ by Ersin KOC

using Swift, SwiftUI, and modern macOS APIs

⭐ Star this repo if you find it useful!

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