The best open source alternative to GlassWire is Portmaster. If that doesn't suit you, our users have ranked more than 50 alternatives to GlassWire and many of them is open source so hopefully you can find a suitable replacement. Other interesting open source alternatives to GlassWire are simplewall, TrafficMonitor, Fort Firewall and Sniffnet.
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.
Shows real-time network speed, CPU, and memory usage on Windows via a floating window or taskbar widget. Features customizable skins, historical traffic stats, resource monitoring, and lightweight operation for home or advanced users. Free and open-source.
Standalone firewall for Windows 7 and later featuring flexible rules by application, address, or protocol, wildcards, parent process filtering, SvcHost controls, blocklists, bandwidth graphs, traffic stats tracking, speed limits, and real-time network monitoring.
Sniffnet is a network monitoring tool to help you easily keep track of your Internet traffic.
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...
InviZible Pro uses DNSCrypt Protocol, Tor and i2pd (I2P Daemon) (PurpleI2P) to achieve maximum security, privacy and comfortable use of the Internet.
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.
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.
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.
A lightweight, highly customizable system tray application that monitors and displays real-time network speeds for Windows.
BitMeter OS keeps track of how much you use your internet/network connection, and allows you to view this information in a variety of ways.
Austria
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China
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Powerful control for the tech-savvy. More free firewall blocking options than Glasswire, which only allows 2 blocks for free.