Duo Security
Duo stops phishing and unauthorized logins by adding a second layer of verification every time someone accesses your business accounts.
Overview
Stolen passwords cause most small business breaches. Duo Security blocks that attack by requiring a second verification step, like a phone tap or fingerprint, before anyone gets into your systems. Cisco owns Duo, and the product serves teams from 1-person shops to large enterprises. The free plan covers up to 10 users at no cost, making it a genuine starting point for very small teams. Paid plans begin at $3 per user per month and add features like single sign-on, phishing-resistant authentication, and the ability to check whether a device is managed before granting access. Room and Board onboarded roughly 1,000 employees in under 30 days, and Lyft's former CISO said Duo improved security while making life easier for employees. Gartner Peer Insights named Cisco a 2026 Customers' Choice for User Authentication.
Features
- Free plan for up to 10 users at $0 per user per month
- Multi-factor authentication protects against stolen credentials and account takeover
- Single sign-on lets employees log in once to access all connected applications
- Trusted Endpoints checks whether a device is registered before allowing access
- 30-day free trial with activation in minutes and no long-term commitment required
Best for
Duo works best for small businesses that rely on cloud apps like Microsoft 365 or Google Workspace and want to stop password-based breaches without hiring an IT team. It fits especially well when the owner needs a free starting point for a small team and the option to grow into paid features later.
Why this SMB score
Duo earns a strong score because the free tier removes the cost barrier for very small teams, setup takes minutes, and the $3 entry-level paid plan delivers phishing-resistant MFA and single sign-on that directly address the most common small business security threats.