TCPBlock has been discontinued. Similar apps include Little Snitch. It's paid, but TinyWall and Gufw are free. Other options are CacheGuard Gateway, Radio Silence, TripMode and Flying Buttress. In total there are seven Firewalls like TCPBlock for Mac, Windows, Linux and self-hosting.
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.
Austria
EU
TinyWall is a free software to harden and control the advanced firewall built into Windows Vista, Windows 7 and Windows 8. TinyWall includes a combination of features that sets it apart from both commercial and freeware firewalls: TinyWall does not annoy you with popups at all...
HungaryEU
Gufw is an easy, intuitive way to manage your Linux firewall. It supports common tasks such as allowing or blocking pre-configured, common p2p, or individual ports port(s), and many others! Gufw is powered by Uncomplicated Firewall (ufw).
SpainEU
CacheGuard Gateway is a free, open-source network security appliance for startups, growing businesses, and SMEs/SMBs that need enterprise-grade protection without the complexity or cost.
FranceEU
Radio Silence lets you block individual apps from accessing the internet. It never throws pop-ups on the screen, and is completely invisible.
FinlandEU
Outbound firewall for apps, blocking apps from accessing internet. Useful for reducing data usage when tethering to mobile data, or on a slower wifi connection.
Switzerland
As Apple's built-in Firewall preferences improves in both functionality and security, I will be aiming Flying Buttress more at users who need the advanced firewall configuration, logging, and IP sharing options found in Flying Buttress.
