What "free" means for antivirus
Antivirus is one of the categories where "free" gets stretched the most — plenty of "free" security suites are actually 30-day trials of the paid product, or a scanner so limited it only detects threats without removing them. The five below all have a genuinely permanent free tier: real-time protection included, no expiry, though each draws the paid-upgrade line in a different place.
The five tools
- Microsoft Defender — already built into Windows, no separate install needed. Real-time protection, ransomware protection and firewall are all included at no cost, and it updates through Windows Update rather than a separate app. The trade-off is fewer extras (no VPN, no password manager) compared to third-party suites, but as a baseline it's solid and requires zero setup.
- Avast Free Antivirus — real-time scanning, a basic firewall and a Wi-Fi security check in the free tier. Historically bundled extra offers during install, so use the custom-install path and read every screen (see our safety checklist for exactly what to watch for).
- AVG AntiVirus Free — under the same parent company as Avast, with a near-identical free feature set: real-time protection, email scanning and a file shredder. If you've tried one and want to compare, the other is worth a quick look since detection engines are shared.
- Bitdefender Antivirus Free — a deliberately minimal free tier: core real-time malware protection with almost no extra screens, notifications or upsells during normal use. Fewer bundled features than the others on this list, but a clean, low-interruption experience if that's what you want.
- ClamAV — open source, primarily on-demand scanning rather than continuous real-time protection, and more commonly used on servers and by technical users than as a everyday desktop antivirus. Included here because it's a genuine outlier: fully open source, so the detection logic itself is publicly auditable, not just the interface.
Antivirus tools are one of the most impersonated categories of software online — always download from the publisher's own domain, never a search-result mirror. Every listing above links to the official source on FreeSoftwareX.
What the free tiers usually don't cover
Across all five, the paid-upgrade line tends to sit in similar places: VPN access, dedicated ransomware rollback, identity-theft monitoring, and priority support are almost always paid extras. None of that means the free tier is crippled — core real-time malware protection is present in all five — just that these specific add-ons are where the free/paid line gets drawn.
Why one is enough
Running two real-time antivirus programs simultaneously is a common mistake — they compete for the same system hooks and can actually reduce protection while definitely slowing your machine down. Pick one real-time tool from the list, and if you want a second opinion, use an on-demand scanner (like ClamAV, or your chosen tool's own manual scan) occasionally rather than running two at once.
Compare all five side by side
Full listings, official links and license details for every antivirus tool on FreeSoftwareX.
Frequently asked questions
For most home users, a maintained free antivirus plus safe browsing habits (like the checks in our software safety checklist) covers the everyday risk. Paid suites add convenience features — VPN, identity monitoring — rather than fundamentally stronger core protection.
Not necessarily — independent testing labs regularly rate Defender's detection competitively with paid suites. Third-party tools mainly add extra features on top, not a fundamentally different level of core protection.
This list only includes tools with a genuinely permanent free tier, not a trial labelled "free." Tell us if there's a tool you think qualifies and we'll take a look.