Best FREE Antivirus Software 2025: Top-Rated for Windows & Mac Protection

In today’s digital world, where cyber threats are more advanced than ever, having strong antivirus protection is no longer optional—it’s essential. Whether you’re a Windows or Mac user, free antivirus software in 2025 offers reliable protection against malware, ransomware, phishing, and zero-day attacks without costing a cent.

Modern cybersecurity tools are smarter, lighter, and powered by AI-driven detection systems. What’s even better? Many free antivirus programs now offer security features that used to be exclusive to premium plans—like real-time protection, VPNs, and password managers.

In this guide, we’ll explore the top free antivirus software 2025, compare their strengths, and understand how their CVSS (Common Vulnerability Scoring System) scores reflect real-world security performance.

Why You Need Antivirus in 2025

Cyberattacks are getting more sophisticated, targeting both individual users and businesses. With ransomware-as-a-service, phishing kits, and AI-generated malware, the risks have multiplied.

Even if you practice safe browsing, malware can sneak in through:

• Fake emails or attachments
  
  

• Infected USB drives
  
  

• Compromised websites or downloads
  
  

• Software vulnerabilities
  
  

An antivirus program acts as your first line of defense—detecting, quarantining, and removing malicious threats before they cause damage.

What Is a CVSS Score and Why It Matters

The CVSS score (Common Vulnerability Scoring System) measures the severity of software vulnerabilities on a scale of 0 to 10.

• 0–3.9: Low severity
  
  

• 4.0–6.9: Medium severity
  
  

• 7.0–8.9: High severity
  
  

• 9.0–10.0: Critical severity
  
  

Antivirus developers use these scores to assess and patch vulnerabilities in their software. A higher CVSS score for detected vulnerabilities means greater risk—but also highlights how effectively antivirus software can identify and fix them.

In short, a lower CVSS vulnerability score for the antivirus itself means a stronger, more secure program.

Top 5 Free Antivirus Software for 2025

Below are the best free antivirus software tools that provide robust protection for Windows and Mac users. Each was evaluated based on malware detection rate, performance impact, features, and overall security effectiveness.

1. Bitdefender Antivirus Free Edition

Best for: Real-time threat detection and low system impact

Bitdefender continues to dominate the antivirus landscape with its lightweight yet powerful protection. Its 2025 version uses advanced AI and cloud-based scanning to detect threats instantly.

Key Features:

• Real-time malware and ransomware protection
  
  

• Cloud-based scanning for fast performance
  
  

• Anti-phishing and anti-fraud detection
  
  

• Auto-pilot mode for hands-free protection
  
  

CVSS Score: Low vulnerability rating (2.1/10) — Bitdefender regularly updates its software to patch potential exploits.

Why It’s Great:
Perfect for users who want simple, automatic protection without intrusive notifications.

2. Avast One Essential (Free)

Best for: All-in-one security suite with extra privacy tools

Avast One Essential is more than just an antivirus—it’s a full security toolkit. The 2025 version includes system cleanup tools, a free VPN (with limited bandwidth), and identity protection features.

Key Features:

• Real-time malware and spyware protection
  
  

• Built-in firewall and phishing shield
  
  

• Free VPN and password manager
  
  

• Performance optimizer for Windows and Mac
  
  

CVSS Score: Medium (4.8/10) — Avast fixes vulnerabilities quickly through auto updates.

Why It’s Great:
Ideal for users looking for complete protection beyond traditional antivirus.

3. AVG Antivirus Free

Best for: Strong malware detection and reliable updates

Owned by the same company as Avast, AVG Antivirus Free focuses on simplicity and solid performance. It offers real-time protection and quick scanning capabilities for both Windows and macOS.

Key Features:

• AI-based threat detection
  
  

• Email protection and phishing defense
  
  

• File shredder for privacy
  
  

• Scheduled scans
  
  

CVSS Score: Medium-Low (3.9/10) — Regular updates make it one of the most secure free antiviruses.

Why It’s Great:
Great for users who want consistent, automatic updates and proven malware detection.

4. Microsoft Defender (Windows Security)

Best for: Built-in protection for Windows 10 & 11 users

Windows Defender has evolved into a highly capable antivirus solution that’s deeply integrated into the Windows OS. In 2025, it rivals many paid options in detection accuracy.

Key Features:

• Real-time virus, ransomware, and spyware protection
  
  

• Cloud-delivered protection powered by Microsoft threat intelligence
  
  

• Integration with Windows Firewall and SmartScreen
  
  

• Minimal system impact
  
  

CVSS Score: Very Low (1.9/10) — Microsoft’s continuous security updates keep Defender highly secure.

Why It’s Great:
Perfect for users who prefer a built-in, maintenance-free solution with solid protection.

5. Avira Free Security Suite

Best for: Lightweight protection with privacy features

Avira is known for its speed and minimal resource use. The 2025 version includes an updated malware engine, VPN, and identity theft protection.

Key Features:

• Real-time protection against viruses and Trojans
  
  

• Free VPN with limited data
  
  

• Password manager
  
  

• System optimizer for performance boost
  
  

CVSS Score: Low (2.7/10) — Avira’s cloud-based protection quickly neutralizes new threats.

Why It’s Great:
Excellent for users on older or low-spec computers who want a fast, reliable antivirus.

Bonus: For Mac Users

While Macs are less frequently targeted by malware, threats are increasing. The following free antivirus programs are best for macOS users:

• Avast Security for Mac – Provides real-time protection and web shield.
  
  

• Bitdefender for Mac (Free Edition) – Offers ransomware protection and safe browsing.
  
  

• Sophos Home Free – Ideal for families, with centralized management for multiple Macs.
  
  

Each provides essential protection without slowing down your device.

How to Choose the Right Free Antivirus in 2025

When selecting an antivirus, consider the following:

1. Detection Rate: Choose tools with 99%+ malware detection accuracy.
   
   

2. System Impact: Lighter antivirus programs are better for older PCs or laptops.
   
   

3. Privacy Protection: Check if the antivirus collects data or includes a VPN.
   
   

4. Update Frequency: Regular updates ensure the latest virus definitions.
   
   

5. CVSS Score: Review reported vulnerabilities to understand product security stability.
   
   

Final Thoughts

The best free antivirus software in 2025 proves you don’t have to pay a premium to stay safe. Programs like Bitdefender, Avast, and Microsoft Defender deliver professional-grade protection for everyday users.

While free antivirus tools provide excellent baseline protection, combining them with good browsing habits, regular updates, and CVSS awareness ensures maximum safety. Whether on Windows or Mac, investing time in the right antivirus now can save you from costly threats later.