Apps similar to Picosnitch include Portmaster, which is open source with a free version. Other options are GlassWire, Traffic Light, Little Snitch and OpenSnitch. In total there are nine Firewalls like Picosnitch for Linux, Mac, Windows and Android.
Free, open-source privacy suite monitoring all network activity, blocking unwanted connections, using trusted filter lists for ads and malware, enforcing DNS-over-TLS, providing custom app and global rules, and supporting advanced privacy management.
Austria
EU
Visualizes real-time and historical network activity, delivers alerts for suspicious behavior and unknown connections, manages firewall rules, reports DNS and system changes, identifies remote hosts, monitors app usage, supports remote monitoring, and detects possible threats.
United States
Traffic Light is an open-source tool for tracking your network usage while ensuring total privacy. Inspired by Internet Speed Meter and GlassWire.
Firewall application for monitoring and controlling outbound network connections, notifying users of attempted access, supporting rule-based blocking, real-time alerts on suspicious activity, and preventing unauthorized data transmission on macOS systems.
AustriaEU
GNU/Linux firewall enabling interactive outbound network filtering, outbound application control, blocking of ads and malware domains, centralized GUI node management, input policy configuration, SIEM integration, real-time alerts, and user-level rule customization.
ItalyEU
Free shared-source firewall for macOS blocking unknown outbound connections unless approved, alerts for unauthorized activity, helps detect malware, blocks OS or app data transmissions, no ads or tracking, audit-ready code on GitHub, enterprise event monitoring.
United States
Monitors all network activity on Mac, blocks specific domains, websites, or entire apps, shows hostnames instead of IPs, supports DNS over HTTPS, provides traffic charts, uses fast system extension, developer-friendly, one-time purchase with no subscription required.
United States
As soon as you’re connected to the Internet, your apps can send whatever they want to wherever they want, unnoticed by you, because all of this happens invisibly under the hood.
AustriaEU
Netherlands