Sentinel app icon

Sentinel by Guangyu Song

See what your Mac is talking to.

A private network monitor for understanding app connections, mapping destinations, and creating local allow or block rules.

Quiet by default

Built for attention, not anxiety.

Sentinel opens on a live map and groups connections by app, so the first thing you see is behavior, not a wall of processes.

Rules stay local. History is bounded. No analytics or tracking SDKs are included in the app.

Map-first monitor App icons and grouped system traffic Local privacy posture User-approved filtering

Local-first privacy

Your connection history belongs on your Mac.

No tracking

The app does not include advertising SDKs, analytics SDKs, or automatic crash-report uploads.

No silent IP lookup service

Destination geolocation uses a bundled GeoIP database where available.

Bounded retention

Connection history can be live-only or retained locally for a limited period.

Guangyu Song

Sentinel is being prepared for the Mac App Store.

For questions, testing, or privacy requests, contact sentinel@guangyusong.com.