In short: Cisco Duo vs Microsoft Authenticator comes down to scope. Microsoft Authenticator is the app for Microsoft Entra ID MFA, strongest when Entra is your identity hub. Cisco Duo is an independent identity security platform covering many identity providers, VPNs, Windows and macOS logon, RDP, SSH and on-premises apps. Duo can also act as an external MFA method inside Entra ID.
Two different kinds of product
It is easy to compare the apps, but the real comparison is between the platforms behind them.
Microsoft Authenticator is the mobile app for Microsoft Entra ID (and personal Microsoft accounts). It handles push approvals with number matching, passkeys, passwordless phone sign-in and one-time codes, and it is controlled by Entra ID's authentication methods and Conditional Access policies. If Entra ID is the front door to everything, Authenticator is the natural default.
Cisco Duo is an identity security platform in its own right. Its Duo Mobile app is one part of a service that adds MFA, single sign-on, device trust and identity threat detection in front of applications regardless of which identity provider they use, including systems that never touch Entra ID.
Side-by-side comparison
| Cisco Duo | Microsoft Authenticator (with Entra ID) | |
|---|---|---|
| Primary scope | Any app or system Duo integrates with, across identity providers | Sign-ins that go through Microsoft Entra ID |
| Push approval | Duo Push, with Verified Duo Push (code entry) configurable by policy or risk | Push with number matching, enforced for all Authenticator push notifications |
| Phishing-resistant options | Passkeys, platform authenticators and FIDO2 keys (Essentials and above) | Device-bound passkeys in Authenticator, plus FIDO2 keys and Windows Hello for Business |
| Windows and macOS logon | Duo agents for Windows Logon, RDP and macOS logon, with offline access | Through Microsoft's own sign-in technologies, such as Windows Hello for Business |
| VPNs and RADIUS | SAML through Duo SSO, or RADIUS and LDAP through the Authentication Proxy | Entra ID SAML for supporting VPNs, or RADIUS through the NPS extension (which uses one-time codes or approve/deny, not number matching) |
| Linux SSH and on-premises apps | Duo Unix, the Authentication Proxy and APIs | Depends on the app supporting Entra ID or the NPS extension |
| Device trust | Trusted Endpoints (Essentials), health checks (Advantage), security agent checks (Premier) | Conditional Access device compliance, usually with Microsoft Intune |
| Adaptive risk | Risk-based authentication in Advantage and Premier | Risk-based Conditional Access through Entra ID Protection (P2) |
| Smartwatch approvals | Duo Mobile companion support for Apple Watch and Wear OS | Authenticator cannot be used on Apple Watch, and number-matching pushes cannot be approved on wearables |
| Licensing | Per-user Duo editions; Duo Free up to 10 users | App is free; MFA policy features depend on the Entra ID licence |
Neither product is better in every row. The right answer depends on how much of your estate lives inside Microsoft's world.
Licensing in plain terms
Microsoft: the Authenticator app itself costs nothing. Microsoft's security defaults, which turn on MFA for everyone with fixed rules, are available to all Entra ID customers. Conditional Access, which lets you decide when MFA is required, needs Entra ID P1, which is included in Microsoft 365 Business Premium. Risk-based Conditional Access needs Entra ID P2 (Entra ID Protection).
Duo: licensed per user by edition. Duo Free covers up to 10 users; Essentials, Advantage and Premier add features in turn. See Cisco Duo pricing and ask us for a quote.
So the question is rarely "free app versus paid app". It is whether your existing Microsoft licences already cover what you need, or whether Duo fills gaps they leave.
Using Duo and Microsoft together
Many organisations use both. Duo offers a Microsoft Entra ID: External MFA application, which lets Duo satisfy Entra ID's MFA requirement. Microsoft previewed this framework as external authentication methods (EAM) and gave it the name external MFA when it left preview in early 2026; Duo renamed its application to match in March 2026, and applications created before then keep the old name. Entra ID still evaluates Conditional Access and makes the access decision; when MFA is needed, users are sent to Duo and approve with Duo Push, Verified Push or a passkey in the Universal Prompt. It needs Entra ID P1 or P2. Unlike the older Conditional Access custom-control approach, a Duo login through external MFA counts as MFA in Entra ID, so it satisfies policies that require multifactor authentication.
Points to know:
- Guest and cross-tenant users need extra configuration (a separate client ID and matching user aliases in Duo) to use Duo
- Microsoft notes that external MFA does not work during Windows 10 device set-up and has no plans to add it; Windows 11 is needed for that scenario
- Users can end up with both Authenticator and Duo registered, so decide which one is the default and tell users
The alternative is to federate Microsoft 365 through Duo Single Sign-On, making Duo the identity provider. Our Duo for Microsoft 365 and Entra ID page covers the options in detail.
When each makes sense
Microsoft Authenticator on its own tends to suit organisations where:
- Nearly every application signs in through Entra ID
- You already have Entra ID P1 or P2 (for example through Microsoft 365 Business Premium) and Intune for device compliance
- VPN and server access are already covered, or not needed
Cisco Duo tends to suit organisations where:
- Important systems sit outside Entra ID: VPNs and firewalls, Windows servers and RDP, Linux SSH, on-premises or industry-specific applications
- You use more than one identity provider, or Google Workspace alongside Microsoft 365
- You want one consistent MFA experience and policy across everything, including Windows and macOS logon
- You want device health and VPN-less access options without changing identity provider
- Some staff need hardware tokens or smartwatch approvals
How we help you decide
We supply both Duo and Microsoft 365 through Forever Group, so we have no reason to push one over the other. We will look at which applications and systems you need to protect, what your current Microsoft licences already include, and where the gaps are, then recommend the simplest design. That might be Microsoft alone, Duo alone, or Duo as an external MFA method in Entra ID. Contact us for an impartial review.
How Forever Systems supplies and supports Cisco Duo
We supply, set up and support Cisco Duo for UK organisations, from small teams and schools to multi-site businesses.
- Edition selection: Duo Free, Essentials, Advantage or Premier, matched to your users, applications and compliance needs
- Integration design: Microsoft 365 and Entra ID, Google Workspace, AWS, VPNs and firewalls, Windows and macOS logon, RDP and RD Gateway, the Authentication Proxy and Duo Single Sign-On
- Device trust: Trusted Endpoints, device health policies and Duo Desktop, alongside your MDM
- Roll-out: user enrolment, communications, hardware tokens for staff without smartphones, and help desk processes that stop MFA fatigue
- Ongoing support: policy tuning, reporting, Cyber Essentials and cyber insurance evidence, renewals and licence changes
Forever Systems Ltd is an independent IT and cyber security provider and also supplies the wider Cisco Secure portfolio.
Want a Cisco Duo quote, trial or roll-out plan?
Tell Forever Systems what you need and we will come back to you by email with options, not a hard sell.
Contact usFrequently asked questions
Is Cisco Duo better than Microsoft Authenticator?
Neither is better in every case. Microsoft Authenticator is a strong choice when almost everything signs in through Entra ID. Duo is broader, covering VPNs, Windows and macOS logon, RDP, SSH and on-premises apps across identity providers, and adds device trust and risk-based options.
Can I use Duo for Microsoft 365 MFA?
Yes. Duo's Microsoft Entra ID: External MFA application lets Duo satisfy Entra ID's MFA requirement, and needs Entra ID P1 or P2. Alternatively, Microsoft 365 can be federated through Duo Single Sign-On.
Is Microsoft Authenticator free?
The app is free. Basic MFA through security defaults is available to all Entra ID customers, but Conditional Access needs Entra ID P1 (included in Microsoft 365 Business Premium), and risk-based Conditional Access needs Entra ID P2.
Does Microsoft Authenticator use number matching like Verified Duo Push?
Yes. Microsoft enforces number matching for all Authenticator push notifications. Verified Duo Push works in a similar way, with the user typing the code from the login screen into Duo Mobile, and Duo admins can choose when to require it.
Can Duo and Microsoft Authenticator be used together?
Yes. Many organisations use Duo as an external MFA method in Entra ID, or use Duo for VPN, server and logon MFA while Microsoft handles Entra ID sign-ins. It is best to choose one default method per user to avoid confusion.