The best free cybersecurity tools can cover most of the basics a small business needs: antivirus, a password manager, multifactor authentication, safe DNS, breach alerts and phishing training. Microsoft Defender, Bitwarden, Quad9 and Have I Been Pwned cost nothing and protect against the most common attacks. US organizations can also use free services from CISA, the national cyber defence agency. This guide lists ten free tools, what each one protects and where free stops being enough.
Key takeaways
- Free tools can cover antivirus, passwords, MFA, DNS filtering, breach alerts and phishing tests.
- Turn on the security already included in Windows, Microsoft 365 and Google Workspace before buying anything.
- CISA offers free vulnerability scanning and resources to eligible organizations.
- Open-source tools such as Wazuh and GoPhish are free but need time and skills to run.
- Free tools rarely include 24/7 monitoring or support, which is where paid services earn their cost.
Which are the best free cybersecurity tools? Quick picks
Each tool below is free for small businesses, either completely or through a generous free plan. Together they cover the controls that stop most everyday attacks.
| Tool | Best for | Platforms / type | Free option |
|---|---|---|---|
| Microsoft Defender Antivirus | Built-in malware protection on Windows | Windows 10 and 11 | Yes, built in |
| Bitwarden Free | Free password manager | All major platforms | Yes, free plan |
| Microsoft and Google built-in security | Securing email and accounts you already pay for | Microsoft 365, Google Workspace | Included |
| Quad9 | Blocking malicious websites with free DNS | Any network or router | Yes, free |
| Have I Been Pwned | Alerts when company emails appear in breaches | Web service | Free domain breach alerts |
| CISA Cyber Hygiene Services | Free external vulnerability scanning | Remote service | Yes, for eligible organizations |
| Cloudflare Free plan | Protecting a business website | Website and DNS | Yes, free plan |
| GoPhish | Free phishing simulations | Self-hosted | Yes, open source |
| Wazuh | Free security monitoring for technical teams | Self-hosted, cloud option | Yes, open source |
| CIS Controls and Benchmarks | A free security checklist and hardening guides | Guidance documents | Yes, free to download |
How we chose: We chose tools that are genuinely free for small businesses, maintained by reputable organizations, and that address the most common causes of breaches: stolen passwords, phishing, unpatched devices and malware. Features and plans change often, so confirm current pricing on each vendor’s site before you buy. We do not accept payment for placement in this list.
Can a small business stay secure with free tools?
Yes, for the basics. Most attacks on small businesses use stolen passwords, phishing emails or unpatched software, and free tools can address all three. The key is to turn on what you already have, use a password manager with MFA everywhere, keep devices updated and train staff to spot scams.
Free tools usually lack 24/7 monitoring, support and central management. As your business grows, or if you handle sensitive data, paid services fill those gaps. CISA keeps a public list of free cybersecurity services and tools worth bookmarking.
What should you secure first?
- Turn on MFA for email, banking and admin accounts.
- Use a password manager and unique passwords.
- Turn on automatic updates for every device; see patch management best practices.
- Back up important data, with one copy offline.
- Train staff on phishing and payment fraud.
The best free cybersecurity tools reviewed
1. Microsoft Defender Antivirus: best for built-in malware protection on Windows
Microsoft Defender Antivirus is included with Windows and performs well in independent tests. For many small offices, keeping it turned on, updated and paired with automatic Windows updates is enough basic malware protection.
- Strengths: Already installed, no extra cost, regular updates, good test results.
- Watch out for: No central dashboard on the free version; business features need Defender for Business.
Official site: microsoft.com
2. Bitwarden Free: best for free password manager
Bitwarden’s free plan gives unlimited passwords across all devices, and a free two-person organization lets a very small team share logins. It is open source and regularly audited.
- Strengths: Unlimited passwords, open source, works everywhere.
- Watch out for: Team sharing beyond two people needs a paid plan.
Official site: bitwarden.com
3. Microsoft and Google built-in security: best for securing email and accounts you already pay for
Microsoft 365 security defaults and Google Workspace security settings turn on MFA, block legacy sign-ins and add phishing protection at no extra cost. Many breaches happen because these settings were never switched on. Our guides to securing Microsoft 365 and securing Google Workspace show where to find them.
- Strengths: Already included, large impact, quick to enable.
- Watch out for: Advanced protection, such as attachment sandboxing, needs higher plans.
Official site: learn.microsoft.com
4. Quad9: best for blocking malicious websites with free DNS
Quad9 is a free, privacy-focused DNS service from a Swiss nonprofit that blocks access to known malicious domains. Changing your router’s DNS settings protects every device on the office network.
- Strengths: Free, simple to set up, nonprofit, privacy-focused.
- Watch out for: No reporting dashboard or custom block lists.
Official site: quad9.net
5. Have I Been Pwned: best for alerts when company emails appear in breaches
Have I Been Pwned lets you check whether email addresses appear in known data breaches. Domain owners can verify their domain and receive free email alerts when company addresses appear in a new breach; searching the whole domain on demand needs a paid subscription. See our guide on checking if your email was in a data breach.
- Strengths: Trusted, free, simple alerts.
- Watch out for: On-demand domain searches and API access need a paid subscription.
Official site: haveibeenpwned.com
6. CISA Cyber Hygiene Services: best for free external vulnerability scanning
CISA offers free vulnerability scanning of internet-facing systems to eligible organizations, including many critical infrastructure businesses, and publishes a catalogue of free tools. It is a strong starting point for US organizations in sectors such as healthcare, water and manufacturing.
- Strengths: Free, run by the US government, regular reports.
- Watch out for: Eligibility rules apply; it only scans internet-facing systems.
Official site: cisa.gov
7. Cloudflare Free plan: best for protecting a business website
Cloudflare’s free website plan adds DDoS protection, a content delivery network, free SSL and basic firewall rules to a website. It is one of the easiest ways to make a small business site harder to attack. Our comparison of AWS WAF vs Cloudflare WAF covers the paid options.
- Strengths: Free DDoS protection and SSL, faster website, easy setup.
- Watch out for: Advanced firewall rules and bot protection need paid plans.
Official site: cloudflare.com
8. GoPhish: best for free phishing simulations
GoPhish is an open-source framework for running phishing simulations against your own staff. It lets you send test emails, track clicks and show people what to watch for.
- Strengths: Free, flexible, widely used by security teams.
- Watch out for: You must host and configure it yourself; no built-in training content.
Official site: getgophish.com
9. Wazuh: best for free security monitoring for technical teams
Wazuh is an open-source security platform for monitoring endpoints, detecting threats and checking configuration. It is powerful but needs someone with technical skills to run it. Our Osquery vs Wazuh comparison explains how it works.
- Strengths: Free, powerful, active community.
- Watch out for: Needs a server and technical knowledge; alerts must be reviewed by someone.
Official site: wazuh.com
10. CIS Controls and Benchmarks: best for a free security checklist and hardening guides
The Center for Internet Security publishes the CIS Controls, a prioritised list of security safeguards, and free hardening guides for common systems. Implementation Group 1 is written for small organizations.
- Strengths: Free, practical, widely recognised.
- Watch out for: Guidance only; you still need to implement the controls.
Official site: cisecurity.org
When should you pay for security tools?
Consider paid tools when you have more than a handful of staff, store customer or health data, need to meet a compliance requirement, or cannot check alerts yourself. The most common upgrades are managed endpoint protection, email security and a business password manager. Our cybersecurity for businesses guide explains how to build a plan.
Related reading
Best Password Managers for Small Business Teams
Best Authenticator Apps for iPhone and Android, Compared
Frequently asked questions
What is the best free antivirus for a small business?
Microsoft Defender Antivirus, built into Windows, is a strong free choice. Keep it turned on and updated, and pair it with automatic Windows updates.
Are free cybersecurity tools safe to use?
Tools from reputable vendors, nonprofits and government agencies are safe. Avoid unknown free tools that ask for broad permissions or come from unofficial download sites.
Does CISA offer free services to small businesses?
CISA offers free resources and guidance to all organizations, and free scanning services to eligible organizations, including many in critical infrastructure sectors.
What free tool should I start with?
Start by turning on MFA for email and installing a password manager such as Bitwarden. These two steps prevent many of the most common attacks.
Is open-source security software free for businesses?
Most open-source tools are free to use commercially, but they need time and skills to set up and maintain. Some offer paid support or hosted versions.
Our verdict
Start with what you already have: Microsoft Defender, the security settings in Microsoft 365 or Google Workspace, and Bitwarden for passwords. Add Quad9 and Have I Been Pwned in an afternoon. Then use our free Cybersecurity Readiness Assessment to find the gaps free tools leave behind.
Sources and further reading
Official vendor websites and public guidance referenced in this guide. Plans and features change, so confirm details with each vendor. Last reviewed: November 2026.
- free cybersecurity services and tools (cisa.gov)
- microsoft.com (microsoft.com)
- bitwarden.com (bitwarden.com)
- learn.microsoft.com (learn.microsoft.com)
- quad9.net (quad9.net)
- haveibeenpwned.com (haveibeenpwned.com)
- cisa.gov (cisa.gov)
- cloudflare.com (cloudflare.com)
- getgophish.com (getgophish.com)
- wazuh.com (wazuh.com)
- cisecurity.org (cisecurity.org)
