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Cybersecurity · head to head

Cisco Duo vs GNAT Pro

Cisco Duo logo

Cisco Duo

Cybersecurity

Trusted access for all users, all devices

From
Free
Free plan
Yes
Full reviewWebsite
GNAT Pro logo

GNAT Pro

Developer Tools

Software development environments and toolchains for Ada, C/C++ and Rust

From
On request
Free plan
No
Full reviewWebsite

The short version

  • Only Cisco Duo has a free tier, so it costs nothing to try first.
  • Each has a real cost: Cisco Duo free tier limited to 10 users maximum; GNAT Pro no pricing published on website; requires contacting AdaCore directly for quotes
  • Prices and features above were last checked on 29 August 2026.

Where they differ

Only the attributes on which Cisco Duo and GNAT Pro actually diverge.

Attributes where Cisco Duo and GNAT Pro differ
AttributeCisco DuoGNAT Pro
Starting priceFreeOn request
Pricing modelsubscriptionquote
Free tierYesNo
CategoryCybersecurityDeveloper Tools

Identical on both: platforms (Web), user rating (Not yet rated).

What people use each for

The jobs each tool is most often brought in to do.

Cisco Duo

  • Eliminating phishing with passwordless authnot GNAT Pro
  • Implementing zero trust with device trustnot GNAT Pro
  • Protecting sessions from hijacking and theftnot GNAT Pro
  • Managing compliance for regulated industriesnot GNAT Pro

GNAT Pro

  • Building certified avionics software meeting DO-178B/C standardsnot Cisco Duo
  • Developing automotive embedded systems with ISO-26262 compliancenot Cisco Duo
  • Integrating Ada, C/C++, and Rust components in single codebasenot Cisco Duo
  • Managing software supply chain vulnerabilities and SBOMsnot Cisco Duo
  • Supporting long-lived software systems spanning decadesnot Cisco Duo

Where each one falls short

Documented limitations, not opinions. Every one is a constraint you would hit in normal use.

Cisco Duo

  • Free tier limited to 10 users maximum
  • Licenses must be purchased in 10-user increments (under 100 users) or 25-user increments (100+ users)
  • Pricing is per-user per-month with minimum purchase increments

GNAT Pro

  • No pricing published on website; requires contacting AdaCore directly for quotes
  • Vendor indicates per-user, per-year subscription model but does not disclose specific costs

Pricing, plan by plan

Cisco Duo

Free
  • FreeFree
    • Multi-factor authentication (MFA)
    • Seamless integrations
    • Authenticator app
  • Essentials$3/month
    • All Free features
    • Duo Directory
    • Phishing-resistant MFA
  • Advantage$6/month
    • All Essentials features
    • Identity intelligence
    • Cisco Identity Intelligence (ISPM, ITDR)
  • Premier$9/month
    • All Advantage features
    • Complete device trust
    • VPN-less remote access

GNAT Pro

On request

No published plan breakdown. See the GNAT Pro review.

Which should you pick?

Choose Cisco Duo if

  • You want to start without paying.
Cisco Duo review

Choose GNAT Pro if

Nothing in the data separates GNAT Pro from Cisco Duo on the points above - pick on price and on how each one feels to use.

GNAT Pro review

Questions people ask

Is Cisco Duo or GNAT Pro better?
Neither clearly leads. Cisco Duo starts at Free and GNAT Pro at On request, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Cisco Duo or GNAT Pro?
Cisco Duo has a free tier; the other does not. Paid plans start at Free for Cisco Duo and On request for GNAT Pro.
Does Cisco Duo or GNAT Pro run on more platforms?
Both run on Web, so platform support will not decide this one for you.
Can I use Cisco Duo for free?
Yes. Cisco Duo has a free tier, so you can try it without paying. GNAT Pro starts at On request.
What is Cisco Duo best used for?
Cisco Duo is most often used for eliminating phishing with passwordless auth, implementing zero trust with device trust, protecting sessions from hijacking and theft, managing compliance for regulated industries. Of those, eliminating phishing with passwordless auth and implementing zero trust with device trust are not what GNAT Pro is typically brought in for.

Answered from the vendors’ own pages

Cisco Duo: How much does Cisco Duo cost?

Cisco Duo Free is $0/user/month (up to 10 users). Paid plans start at $3/user/month (Essentials), $6/user/month (Advantage), and $9/user/month (Premier). Billing is per-user per-month.

Source
GNAT Pro: How much does GNAT Pro cost?

GNAT Pro pricing is not published on the website. Customers must request a pricing quote by contacting AdaCore directly or speaking with a GNAT Pro expert.

Source
Cisco Duo: Is Cisco Duo free to try?

Yes, Duo Free offers multi-factor authentication and seamless integrations at $0/user/month for up to 10 users.

Source
GNAT Pro: What is GNAT Pro licensing model?

GNAT Pro is sold on a per-user, per-year basis with no license locks. Customers can request pricing for their specific needs.

Source
Cisco Duo: What is the minimum purchase for Cisco Duo?

Organizations must buy licenses in 10-user increments for under 100 users, or 25-user increments for 100 or more users. Plans are modifiable at any time.

Source
Cisco Duo: What does the Advantage plan add over Essentials?

Advantage ($6/user/month) adds identity intelligence, Cisco Identity Intelligence (ISPM, ITDR), Duo Passport, session theft protection, Active Directory Defense, and risk-based authentication.

Source
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