PowerMonitor

A retrospective system monitor for Apple Silicon Macs. Most tools show you power and CPU usage right now — PowerMonitor keeps a history, so you can go back and see what your battery, power draw, and top processes were doing 10 minutes or 30 days ago.

Alpha software. Expect rough edges. Feedback welcome.

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Features

• Battery history — charge/discharge level over time, with charging state and estimated time remaining
• Power draw — real-time wattage (positive while charging, negative while discharging)
• CPU by process — per-core usage breakdown for your top processes over the selected window, switchable between stacked-blocks and smooth views
• System info — chip, cores, GPU cores, RAM, battery health and cycle count
• Memory pressure — usage colored by actual kern.memorystatus_vm_pressure_level, not just percentage full
• Sleep assertions — see what's keeping your Mac awake, with system noise filtered out
• Time ranges — 10 minutes, 1 hour, 6 hours, 24 hours, or 30 days, each with axis labels suited to the range
• Hover for detail — every chart shows exact values and timestamps for the sample under your cursor
• Liquid Glass sidebar — real NSGlassEffectView material on macOS 26 (Tahoe) and later, with several switchable presets under View ▸ Glass Style; falls back to standard vibrancy on earlier macOS versions
• Light/dark/system theme, native to macOS
• Runs in the background — a LaunchAgent logs every 60 seconds even while the app itself is closed
• Local only — everything lives in a SQLite database on your machine; nothing is sent anywhere

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Requirements

• macOS 13 (Ventura) or later
• Apple Silicon (M1 or newer)
• macOS 26 (Tahoe) or later for the real Liquid Glass sidebar material — earlier versions fall back to vibrancy automatically, no separate build needed

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Install

1. Download the latest PowerMonitor-*.dmg from Releases
2. Open the DMG and drag PowerMonitor.app into your Applications folder
3. Launch it — on first run, PowerMonitor installs its background logger automatically

Gatekeeper note: the app isn't notarized yet, so right-click → Open on first launch if macOS blocks it.

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How it works

LaunchAgent logger  →  ~/.local/powermon.db (SQLite)  →  PowerMonitor.app
   samples every 60s         local, never synced           reads + renders

PowerMonitor installs a macOS LaunchAgent that samples your system every 60 seconds using the bundled Electron binary — no separate runtime required. Each sample is written to a local SQLite database. The app itself only reads from that database and draws charts over whichever time window you've selected; it never writes to the log on its own.

Each sample records:

• Battery percentage, charging state, amperage, voltage, estimated time remaining
• Top CPU- and memory-consuming processes
• Sleep assertions — anything currently preventing the Mac from sleeping

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Build from source

# Prerequisites: Node.js, npm, Homebrew
brew install create-dmg

git clone https://github.com/kanin-design/PowerMonitor.git
cd PowerMonitor
npm install
npm run build

This packages the app and produces a DMG in the project root.

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Your data

Everything lives locally at ~/.local/powermon.db (SQLite) — nothing leaves your machine.

Inspect it directly:

sqlite3 ~/.local/powermon.db "SELECT ts, battery FROM power_log ORDER BY ts_unix DESC LIMIT 10"

Remove the background logger entirely:

launchctl unload ~/Library/LaunchAgents/com.delfinsoft.powermonitor.plist
rm ~/Library/LaunchAgents/com.delfinsoft.powermonitor.plist

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License

MIT © 2026 Delfinsoft