Keeping your Windows PC secure from viruses and malware is an essential part of being a Windows user. Microsoft has the Windows Security app built-in, but you might prefer something else. However, have you thought of going open-source to secure your system?

There are good reasons to go with free and open-source alternatives to commercial software. In many cases, it’s better, and it is typically free. For instance, there are feature-rich open-source alternatives to PhotoShop to save money. If you use Windows, Linux, or even macOS, you might be looking for a free antivirus alternative backed by the open-source community.

5 ClamWin Free Antivirus

An oldie but goodie

In the XP days, paid antivirus apps like TrendMicro, McAfee, and Norton were common security software suites that came free on your PC with a free trial period. However, once the trial ended, they were essentially "nagware” and broke your computer. While doing tech support, a customer asked about an open-source solution. I discovered ClamWin and was so impressed that I started using it on my XP system. It’s still free and open-source under the GNU GPL. It doesn’t win any awards for an elegant modern UI, but it gets your scans and malware protection done. However, it lacks real-time scanning, but its database is regularly updated. You need to run a virus scan from the app manually to ensure a secure Windows system.

4 Armadito Antivirus

A cross-platform security solution

Another free and open-source alternative to paid security suites is Armado Antivirus. What makes this one unique is that it’s multi-platform, meaning it works on Windows and Linux PCs and servers. One of the notable benefits of ClamWin is it offers real-time protection. It has an intuitive and responsive interface and protects your system from viruses through on-demand scans and virus quarantines. It includes tabs you would expect, like “Scan” and “Status.” It also includes a “Journal” tab that provides you with a list of Armadito activities like quarantined files, app updates, and which user was using during the time of each entry.

3 ClamAntiVirus (ClamAV)

A multi-platform alternative

While Armadito is cross-platform, ClamAV goes the extra mile with multi-platform support for Windows, Linux, and macOS. It has a massive database that is updated regularly with signature-based detection of viruses, trojans, rootkits, worms, and other types of malware. It has user-friendly controls for scheduling folder scans, permitting trusted apps, and deleting suspicious files.

2 The OpenAntivirus Project

Includes email filtering

Another option is the OpenAntivirus Project, a collaborative open-source alternative that provides a virus scanner, disinfection tools, and an email filter. Unfortunately, the project is not actively maintained; however, many users still utilize it. It also has source servers as a foundation for several modern open-antivirus efforts. It offers a modern design and is cross-platform, working with Windows and Linux. It provides virus detection via signatures, pattern matching, and community-driven development.

1 MoonSecure Antivirus

Open-source antivirus for Windows

MoonSecure AV is a straightforward security software suite that has a user-friendly GUI that first-time users will find easy to use. Another benefit is it is light on system resources, making it a good choice for low-end PCs. The Enterprise version is scalable to protect one or multiple PCs remotely on a network. In addition to virus and malware protection, it includes a firewall and support for on-demand system scanning.

Free open-source antivirus protection on multiple platforms

If you want a way to protect your PC or Mac from viruses and other malware, there are some good open-source options to consider. Personally, I have a soft spot for ClamWin since I am a Windows user. It doesn’t have real-time scanning, but it’s nice to have it in my security toolbox so I can get a second opinion if I am not completely satisfied with the Windows Security app results when I run a manual virus scan on Windows 11.