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Error: listen EADDRINUSE: address already in use :::3000
Something is squatting on the port. Maybe the Vite server from a project you closed two days ago. Maybe a Next.js process that survived its terminal. Harbor exists so you never paste lsof -ti :3000 | xargs kill again.
Harbor is a native macOS menu-bar utility that shows every dev server listening on localhost — and lets you act on it in one keystroke. Click the bollard in your menu bar (or hit ⌘⌥P from anywhere): every listening port, the framework behind it, live CPU / memory / uptime, an energy badge when something is quietly burning your battery — and one-click kill, open-in-browser, or jump-to-terminal.
40-second teaser — watch the full 60s demo with sound
| Every listening port | IPv4 + IPv6, grouped by project, with an exposed badge when something is bound beyond loopback — the difference between a dev server and an accidental network service. |
| Framework detection | Next.js, Vite, Rails, Django, Flask, Express, Astro, Remix, FastAPI, Phoenix, Spring Boot, Laravel, and more. System daemons get honest names too (AirPlay, Screen Sharing) instead of pretending to be dev servers. |
| Live vitals | Uptime, CPU, memory, and an energy-impact badge per server — with rolling CPU/memory bar sparklines in the detail inspector. |
| One-keystroke actions | Kill (SIGTERM→SIGKILL with PID-reuse protection), Kill All with enumerated confirmation, multi-select batch kill, open in browser, jump to the owning terminal (Terminal, iTerm2, Warp, Ghostty, WezTerm, kitty, Alacritty, VS Code, Cursor). |
| Keyboard-first | Rebindable global hotkey, arrow-key navigation, type-to-filter, Space to inspect, Esc to dismiss. Right-click the menu-bar icon for a quick menu without opening the panel. |
| Deep visibility | Detail inspector with full command line, working directory, owner app, bind scope, and health. Docker/Kubernetes port-forwards and tunnels (ngrok, cloudflared, ssh -R/-L) are labeled with their real origin. Opt-in view for UDP and stuck non-LISTEN sockets. |
harbor-cli |
list, kill, watch, open from the terminal, with a stable JSON schema for scripting. |
| Light | Dark |
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- Download Harbor.dmg (free)
- Verify the checksum (optional, recommended):
curl -LO https://github.com/ftchvs/harbor/releases/latest/download/Harbor.dmg.sha256 shasum -a 256 -c Harbor.dmg.sha256
- Open the DMG, drag Harbor to Applications, launch it from the menu bar.
Updates arrive in-app through Sparkle with EdDSA-signed appcasts.
Requirements: macOS 14 (Sonoma) or later · Apple silicon or Intel.
Harbor never phones home. No telemetry, no accounts, no network calls except the ones you ask for (opening your server in a browser, checking for updates). The app is Developer ID signed, hardened-runtime, notarized by Apple, and every release ships with a published SHA256.
Harbor is not sandboxed, by necessity — it inspects and signals other processes on your machine, which the App Sandbox forbids. That is also why it is distributed here and not on the App Store.
Harbor's mark is a mooring bollard with a rope — the thing a harbor actually uses to hold vessels safely in place, the way Harbor holds your dev servers in view. The sea-glass arcs are a live, listening port. Deliberately not an anchor, and deliberately not a container.
Read the full launch story on ftchvs.com.