Take total control of your Mac’s network.
See every outbound connection your apps make, by name, and block any of them. Everything runs on your Mac.
The problem
That app is talking to where?
Your Mac makes hundreds of outbound connections an hour that you never see. The tools that can show them either flood you with prompts or print raw IP addresses.
Nothing leaves your Mac.
- Local-only
- No accounts, no cloud sync, no servers of ours. Captured data never leaves the device except by an export you ask for.
- Zero telemetry
- No analytics, no crash reporting, no tracking SDKs. Two optional outbound calls exist, a licence check and an update check, and neither carries your data.
- Dropped before it leaves
- A denied connection is dropped on this Mac before it ever leaves. Block latency is about 9 ms.
Identify
Know every connection by name.
Portwhistle resolves each IP address to the hostname behind it and names the app that opened the connection, as the traffic happens.
category → app → destination
Names, not addresses
Every connection shows the hostname it reached, not a bare IP.
104.18.32.7api.anthropic.com
- Grouped by category, then app, then destination
- Verified app identity, read from the code signature
- Names read from the server name apps send in the clear, never decrypted
- Searchable 30-day history, stored on your Mac
Map
See where your data goes.
A world map of everywhere your apps connect. Pick any country to see which applications reach it, and exactly what they touch there.
Bundled offline
The IP-to-country database ships inside the app. Looking up a destination doesn’t ask anyone.
- Every connection placed on the map in real time
- Pick a country, see the apps behind it
- Block a destination straight from the list
- US United States
- IE Ireland
- SE Sweden
- DE Germany
- NL Netherlands
looked up on your Mac, never online
Control
Two postures. Precise rules. Your call.
Nothing is blocked until you add a rule. Portwhistle starts in monitoring mode and never prompt-floods you.
POSTURE
Watching everything. Blocking nothing.
~9 ms
Default-deny lockdown
Flip to Lockdown and nothing leaves unless you allow it. Flip back to Monitoring to simply watch. Critical system traffic always passes, so you can never lock yourself offline.
- Adobe Creative Cloud BLOCKED
- Dropbox BLOCKED
- Brave BLOCKED
- Spotify ALLOWED
Precision app blocking
Block an app and everything it launches, or block just one destination and keep the app working. Your rules stick around across restarts.
30-day history
A rolling view of everything that connected, stored on your Mac and never in a cloud. Read it, export it, or clear it whenever you like.
- api.statsig.com DROPPED
- featuregates.statsig.com DROPPED
- events.statsigapi.net DROPPED
- api.statsig.com
Watch your Mac’s network in the open.
A local-first network monitor and application firewall. No accounts, no tracking, just a clear view of what your machine is doing and the power to shut anything down.