OpenSnitch vs Portmaster

OpenSnitch is a GNU/Linux interactive application firewall inspired by Little Snitch. It allows users to intercept and control outgoing network connections, providing a high level of security and control over the system's network activity.

Portmaster, made by the Austria-based company Safing, is a free and open-source application firewall for Windows and Linux that gives users visibility into every network connection made by every application on their computer. Rather than just blocking traffic at the network edge, it lets users set per-application rules to allow, block, or restrict specific programs, and can completely isolate an app from the internet if desired. Beyond application-level control, Portmaster blocks ads and trackers system-wide at the DNS level, meaning the protection applies across all applications rather than just a browser. It supports restricting connections by country and blocking specific domains directly. Safing also offers SPN, a separate paid privacy network product, and a Pro tier for Portmaster itself, alongside the free core firewall application.

• Highly customizable
• Real-time monitoring
• Interactive interface
• Open source and free

• Free and open source with a transparent, publicly reviewable codebase
• System-wide DNS-level ad and tracker blocking, not limited to a single browser
• Granular per-application network control not found in most consumer firewalls
• Active development with recent updates and an engaged community

• Steep learning curve
• Limited documentation
• Only compatible with Linux

• No macOS support currently, only Windows and Linux
• More technical than typical consumer security software, aimed at privacy-focused users
• Optional Pro/SPN pricing (80 EUR/year) is not prominently broken down on the main site