5 Best Free Open Source Firewall Software For Windows

Here is a list of best free open source Firewall software for Windows. These open source firewall software are completely free and you can also download and modify their source codes.

These software allow you to control incoming and outgoing network traffic to ensure security. Through some software, you can easily provide system-wide firewall protection. The advantage of system-wide protection is its ability to control the network access of every process and application of a system. Plus, these software let you manually enable or disable the network access of applications and processes. In some, you can also create whitelists and blacklists of applications that can and cannot access the network. Some of the firewall software are browser (Chrome and Firefox) extensions that only restricts network access within a browser. Through browser-based firewall extensions, you can easily restrict access to websites, webpages, and associated elements like images, videos, CSS elements, java scripts, etc.

In few software, you can also view the real-time data of all processes and applications which are using the network with their status. Other important features like Rules (to specify custom firewall rules for applications) and Network Protocol (to toggle between network protocols) are also present in some software. In general, all of these are very capable software and tools that you can use to add firewall protection to your system and browsers. Go through the list to know more about these software.

My Favorite Open Source Firewall Software For Windows:

Simplewall is my favorite software because it offers system-wide firewall protection. Plus, it shows the names of various applications and processes which use the network in real-time. It also lets you manually specify which programs and processes can access the network.

You can also check out lists of best free FirewallOpen Source Bandwidth Monitor, and Open Source Data Recovery software for Windows.


Simplewall is a free open source firewall software for Windows. It is a lightweight firewall software through which you can control and monitor network activity on your computer. To configure various network activities, it offers multiple sections like Blocklist, System Rules, User Rules, Packages, Services, and more. Now, let’s check out the main features of this firewall software.

Main Features:

  • Blocklist: In this section, you can view all the blocked apps and services which are identified as unsafe by this software. You can manually select and enable any blocked app that you want.
  • System Rules: It shows all the enabled and disabled network rules of a system like IGMP, SSDP, LLMNR, UPnP, etc.
  • Settings: From settings, you can enable or disable Microsoft servers services (Microsoft spying and telemetry servers, Microsoft update servers, and Microsoft application servers). In addition to that, you can enable or disable various Network, Security, and Advanced rules.
  • Apps: It shows all the apps which use the network. You can allow or disallow any app from accessing the network.
  • Services: It shows a list of services that use the network. Just like apps, you can allow certain services to use the network and disallow others.
  • Add Rules: It is an advanced feature that lets you create your own rules that you can apply to some or all system apps.

Additional Feature:

  • Network: In this section, you can view various services, programs, and apps that are using the network in real-time along with their port number, destination address, protocol, and connection status.

Final Thoughts:

It is a feature-rich open source firewall software through which you can easily control apps and services which can access the network.


ProgCop is another free open source firewall software for Windows. Using this software, you can easily control the programs and services of your system accessing the network. Plus, it shows a real-time view of processes and applications which are having internet access.

Main Features:

  • Process Viewer: In it, you can view all the process which use internet connection along with their connection status (established, listening, or close wait), local port number, local address, remote address, and PID.
  • Rules: Using it, you can manually add multiple applications in the rules section and either block or unblock them from accessing the network.
  • Settings: It allows you to change the current network protocol of your system to IPv6.

Final Thoughts:

It is one of the simplest open source Firewall software through which you can track the connection status of processes, and also manually enable or disable processes connected with the network.

Cloud Firewall

Cloud Firewall is a free open source firewall extension for Chrome and Firefox web browsers. Through this firewall extension, you can block connections to sites, pages, and web resources (images, videos, etc.) hosted in major cloud services like Amazon, Google, Cloudflare, etc.

Main Features:

  • Popup Menu: In this menu, you can view a list of cloud services that you can block or unblock in one click namely Google, Amazon, Facebook, Apple, Microsoft, and Cloudflare. By blocking a specific cloud service, you can block all the sites, pages, etc., hosted to that cloud service.
  • Allow All/ Block All: In the popup menu, you also get ‘allow all’ and ‘block all’ buttons to allow or block connections from all the mentioned cloud services.


Apart from the six mentioned cloud services, you cannot block any other website or webpage through this firewall extension.

Final Thoughts:

It is a simple and easy to use open source firewall extension through which you can easily block some specified cloud services in just one click.


uMatrix is another free open source firewall browser extension for Chrome and Firefox. Through this extension, you cannot only block websites but also block various elements that a browser requests at the time of loading a website such as scripts, iframes, ads, etc. Plus, it also shows websites and all elements on its popup window.

Main Features:

  • Popup Window: From the popup window of this software, you can easily block the current website and its elements like CCS elements, images, etc., in one click.
  • Real-Time Elements: In its popup window, you can also view the number of all elements associated with a website like the number of cookies, CSS elements, images, media, scripts, frames, etc.
  • Forbid Web Workers: Using it, you can enable or disable all the web workers or Javascripts that run independently.
  • Forbid Mixed Content: It not only lets you block all the websites over the insecure HTTP connection but also block secure HTTP websites with resources that come from an insecure HTTP connection.


  • In this extension, you can only block a website and other elements after loading them once in your browser.

Final Thoughts:

It is another easy to use open source firewall extension for Chrome and Firefox through which you can block websites and their elements.

Firewall Builder

Firewall Builder is the next free open source firewall software for Windows, Linux, and macOS. Using this software, you can apply firewall packages over devices and routers of different platforms such as Linux iPtables, OpenBSD, ASA/PIX HA Cluster, Router ACL, etc. Plus, you can manage the firewall on all devices of the network from this software. Unlike other similar software, it does not offer Firewall protection for the device on which it is installed.

Main Features:

  • Objects: Using it, you can specify the address of devices on which you want to apply the firewall and also manage them through this software. Apart from the address range, you can also specify DNS names, groups, hosts, networks, addresses, etc., from this Object section.
  • New Object: It is a menu through which you can create new clusters, hosts, networks, new address range, IP serves, ICMP services, etc.
  • Create New Firewall: Using it, you can create new firewalls after selecting devices and routers on which you want to apply the firewall.
  • Rules: Using it, you can create custom firewall rules for each device on which you want to apply the firewall.

Additional Feature:

  • Import Existing Configuration: If you already have a firewall configuration file, then you can import it using this feature and quickly apply it over router and devices.


  • This software does not provide firewall protection in the base device in which it gets installed.

Final Thoughts:

It is a really good open source firewall software through which you can apply the firewall on multiple networking devices.

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Naveen Kushwaha

Passionate about tech and science, always look for new tech solutions that can help me and others.

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