When does building SSO make sense?

Building is most defensible for organizations with data-residency requirements, strong privacy constraints, or teams willing to own identity operations on platforms like Keycloak or Authentik. At large user counts, per-seat pricing can tip the math toward self-hosting.

When does buying SSO make sense?

Buying earns its keep when your SaaS catalog is broad, the pre-built connector library saves real integration work, and your team has no appetite for identity oncall. Microsoft Entra ID and JumpCloud both cover the baseline for most organizations without requiring a separate license if you're already in their ecosystems.

What are the main SSO vendors?

Representative vendors include Microsoft Entra ID, Okta SSO, JumpCloud, OneLogin. B4 Pro scores the full set.

What is the 'SSO tax'?

The SSO tax refers to the common practice of vendors charging significantly more for plans that include SSO integration, even though SSO is a basic security feature. It's a real grievance in the market and one reason some teams self-host identity infrastructure.

Security & Compliance · Engineering, IT & AI

Should you build or buy Single Sign-On (SSO)?

Single Sign-On (SSO) software lets users authenticate once and access multiple applications without logging in again. It federates identity across SaaS tools, internal apps, and cloud services using SAML, OIDC, and OAuth 2 standards, centralizing session management and reducing credential sprawl across the organization.

The build-vs-buy decision for SSO turns on whether the labor cost of running a self-hosted identity provider like Keycloak or Authentik competes with what vendors charge, and whether their pre-built SaaS app catalog genuinely saves integration work at your scale; the specifics decide it.

Domain: Security & Compliance
Function: Engineering, IT & AI
Industries: Cross-industry

Last assessed June 2026 · re-scored quarterly via The Continuum.

Build it, buy it, or bridge?

	Build it	Buy it	Bridge (buy, then extend)
Cost shape	OSS IdP licensing free; dedicated identity engineer often approaches Okta's license cost	Per-user SaaS with 'SSO tax' on third-party app integrations	Self-host core IdP; pay for integrations that OSS doesn't cover natively
Time to value	Weeks for core federation; months for a full SaaS app catalog	Days to federate standard apps; full catalog live in weeks	Core running quickly; extend SaaS coverage as catalog grows
Differentiation captured	None; invisible plumbing no customer or partner evaluates	Thousands of pre-built connectors and verified app integrations	Own the core identity policy; buy the long tail of app connectors
AI feasibility today	Keycloak, Authentik, Zitadel explicitly deemed production-ready for self-hosted IAM in 2026	Vendors handle standard evolution; network effect of connectors is hard to replicate	OSS for primary federation; vendor for SaaS-catalog breadth
Who it fits	Developer-heavy orgs with privacy or compliance needs driving self-hosting	Any org with a broad SaaS catalog and no appetite for identity operations	Teams wanting control over core IdP while offloading integration maintenance

The B4 call

B4 has a verdict for Single Sign-On (SSO).

Build, Buy, Bridge, or Beware, with the five-dimension scorecard and the reasoning behind it. Unlock the call, and every other category, with B4 Pro.

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When building Single Sign-On (SSO) makes sense

Running your own SSO infrastructure is a well-documented path in 2026, not a contrarian choice. Keycloak, Authentik, Zitadel, and Authelia are all in production at organizations that need data residency control, have privacy requirements that make routing authentication through a third party unacceptable, or simply want to escape the 'SSO tax' that vendors charge for enabling specific integrations. A 2026 evaluation concluded that the maturity of these platforms has reached a point where self-hosted IAM is a reasonable choice for most technically capable organizations. The build case gets more compelling at large user counts where per-seat pricing compounds, and in developer-forward companies where owning the identity layer fits the existing infrastructure philosophy. The constraint is operational: a dedicated engineer maintaining Keycloak at scale, keeping up with standards evolution, and providing 24/7 SLA is a real cost that the per-seat comparison often ignores.

When buying Single Sign-On (SSO) makes sense

Buying SSO earns its keep when your SaaS catalog is broad and you want the thousands of pre-built application connectors that JumpCloud, Okta, and Microsoft Entra ID maintain. Wiring each new SaaS tool into a self-hosted IdP is straightforward for well-documented apps, but the long tail of niche tools with unusual SAML implementations is where the integration burden accumulates. The network effects of a vendor's connector library are real and hard to replicate from scratch. Buying also makes sense when your engineering team doesn't want to own identity operations as a permanent responsibility: SSO is invisible infrastructure that must work flawlessly at all hours, and the oncall burden of a production identity outage sits on whoever owns the platform. Microsoft Entra ID is particularly attractive if you're already paying for M365, where SSO is effectively included.

Keycloak, Authentik, Zitadel, and Authelia are all in documented production as self-hosted SSO infrastructure. A 2026 evaluation explicitly concluded that the maturity of Authentik, Zitadel, and Casdoor has reached a point where self-hosted IAM is a reasonable choice for most organizations. For developer-heavy companies or those with strong privacy requirements, operating your own identity provider is a well-understood path with real precedent.

The counter-argument is that the labor cost of a dedicated identity engineer maintaining Keycloak at scale often approaches what Okta or Microsoft Entra ID charges. SSO is invisible infrastructure that must work flawlessly at all times, and the 'SSO tax' that vendors charge for enabling third-party integrations is a real grievance, not a fabricated one. Buying earns its keep when your SaaS catalog is broad, your engineering team doesn't want to own identity operations, and the app catalog integrations from JumpCloud or Okta genuinely reduce integration work. The network effects of thousands of pre-built connectors are hard to replicate from scratch.

Representative vendors

Okta SSOMicrosoft Entra ID and 3 more, scored in B4 Pro

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Frequently asked

What is Single Sign-On (SSO)?: SSO software lets users authenticate once and access multiple applications without logging in again. It federates identity across SaaS tools, internal apps, and cloud services using SAML, OIDC, and OAuth 2 standards, centralizing session management across the organization.
When does building SSO make sense?: Building is most defensible for organizations with data-residency requirements, strong privacy constraints, or teams willing to own identity operations on platforms like Keycloak or Authentik. At large user counts, per-seat pricing can tip the math toward self-hosting.
When does buying SSO make sense?: Buying earns its keep when your SaaS catalog is broad, the pre-built connector library saves real integration work, and your team has no appetite for identity oncall. Microsoft Entra ID and JumpCloud both cover the baseline for most organizations without requiring a separate license if you're already in their ecosystems.
What are the main SSO vendors?: Representative vendors include Microsoft Entra ID, Okta SSO, JumpCloud, OneLogin. B4 Pro scores the full set.
What is the 'SSO tax'?: The SSO tax refers to the common practice of vendors charging significantly more for plans that include SSO integration, even though SSO is a basic security feature. It's a real grievance in the market and one reason some teams self-host identity infrastructure.

The B4 Index scores every software category on two axes, strategic differentiation and AI feasibility, to classify it Build, Buy, Bridge, or Beware. See the full methodology.

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