What it does
Portmaster is an open-source application firewall with connection monitoring, per-app rules and DNS-level blocking controls.
Portmaster makes an application's connections visible and lets the user block an individual destination or apply a broader rule. That is useful when a desktop program reaches services that are unrelated to its main task. Review a normal work session before creating restrictive rules so necessary update or sign-in traffic can be recognized. Global and per-app settings serve different scopes. Its DNS-level blocking is part of a local firewall workflow, not a claim that the device becomes anonymous.
Strengths
- Per-application connection visibility and rules
- System-wide DNS blocking controls
Best for
- Desktop users reviewing unwanted application connections
Sources
- Portmaster - Application Firewall by Safing (Oct 26, 2026)
- Portmaster LICENSE (Oct 26, 2026)