OpenSnitch is described as 'GNU/Linux application firewall' and is a Firewall in the security & privacy category. There are more than 25 alternatives to OpenSnitch for a variety of platforms, including Linux, Windows, Mac, Android and iPhone apps. The best OpenSnitch alternative is Portmaster, which is both free and Open Source. Other great apps like OpenSnitch are simplewall, Pi-hole, GlassWire and Fort Firewall.
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.
Simple tool to configure Windows Filtering Platform (WFP) which can configure network activity on your computer.
Blocks ads for all connected devices at the DNS layer without client setup. Provides web control, in-app ad and tracker blocking, DHCP and API support, regex filtering, privacy modes, audit logs, and long-term query analytics for network management.
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.
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.
A powerful tool which extends the functionality of Windows Firewall and provides new extra features which makes Windows Firewall better.
NetGuard provides simple and advanced ways to block access to the internet - no root required.
InviZible Pro uses DNSCrypt Protocol, Tor and i2pd (I2P Daemon) (PurpleI2P) to achieve maximum security, privacy and comfortable use of the Internet.
Minimal Firewall is a portable Windows firewall frontend that alerts users to internet connections without requiring custom kernel modifications or disabling core isolation, striking a balance between TinyWall's security and SimpleWall's functionality.
Tiny Shield keeps your network safe by watching all connections and stopping bad stuff before it can harm your computer. Tiny Shield keeps an eye on everything your Mac connects to, making sure you can see all your internet activity in one place.
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.
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Closest in terms of functionality if looking for an open source alternative that supports windows instead of linux