Every B2B organization building for enterprise customers faces a pivotal decision: should you build Single Sign-On (SSO) in-house or adopt a third-party solution?
Most teams assume SSO is just another login screen. In reality, it’s a protocol-heavy, edge-case-ridden infrastructure layer that affects user experience, security, scalability, and engineering velocity.
This guide is designed to help product and engineering leaders understand the true scope of building SSO, hidden operational burdens, and when it makes strategic sense to buy.
What is enterprise SSO?
Enterprise-grade authentication allows users to access multiple applications using one set of credentials. It integrates with identity providers (IdPs) like Okta, Entra (Azure AD), and Google Workspace, streamlining authentication while meeting complex security and compliance requirements.
An effective SSO implementation improves user experience, reduces password fatigue, and helps close enterprise deals.
What you need to build for enterprise SSO
Core SSO components
Enterprise SSO isn’t just one simple login feature. Beyond the core authentication process, you'll need to handle complexities such as multi-tenancy, integrations with various identity providers (IdPs), attribute mapping, and robust admin tools. Here’s a detailed breakdown of all the components you need to build in-house:
What you'll need to build
1. Core SSO functionality
Enterprise customers expect both push (IdP-initiated) and pull (SP-initiated) flows
- SAML 2.0 implementation
- OIDC (OpenID Connect) support
- SP & IdP-initiated flows
- Metadata exchange (XML parsing, signing certs)
- Redirect handling, RelayState logic
- Single Logout (SLO) workflows
2. Security features
Avoid common attack vectors and meet enterprise infosec standards
- Assertion signature validation
- Token expiry and replay protection
- Clock skew handling
- Audience URI and Issuer validation
- Certificate rotation and revocation support
- HTTPS enforcement for ACS and metadata
3. Multi-tenant support
SSO configurations vary for each customer's Organization
- Tenant (org) specific SSO config (certificates, entity IDs, ACS URLs)
- Per-org login route resolution (domain-based, email-based)
- Isolated session handling across tenants
Attribute and role mapping
Need to map clients' custom attributes correctly
- Support for custom user attributes (e.g., department, role)
- Map SAML assertions (or OIDC claims) to user schema
5. Customer-facing admin UI
Without self-serve admin UI, every SSO configuration becomes a support task
- Configure SSO connections
- Manual and automatic certificate updates
- Test SSO config and activate
- Auth-related logs
- Error messages and rollback options
6. QA and interoperability testing
Each IdP behaves slightly differently
- Test SSO with Okta, Microsoft Entra, Google and all SAML, OIDC identity providers
- Validate IdP and SP-initiated flows
- Negative test cases (invalid certs, expired assertions, role mismatch)
- Browser-based login tests (cookies, redirects, CSP)
7. Config tool for customer support and success
Use admin portal as internal config tool to track each customer's SSO config, reduce escalations, and enable faster customer onboarding
- Internal dashboard to view SSO status per org
- Ability to impersonate on behalf of customers
- Configure and test SSO setup
- Trigger metadata refresh, cert updates, and toggle flows
8. Edge case handling
Without robust error handling, logins will silently fail
- Broken RelayState
- Expired tokens
- Mismatched audiences
- Invalid bindings (POST vs. Redirect)
9. Logging and monitoring
Support teams need visibility to troubleshoot without escalating to engineering
- Auth event logging and trace IDs
- Real-time logs for login failures
- Admin visibility into who authenticated when
- Alerts for cert expiry and login issues
10. Maintenance and support
Identity protocols evolve, and staying compliant means ongoing engineering time.
- Ongoing upkeep of SDKs and libraries
- Continuous updates for SAML/OIDC spec changes
- Certificate rotation tooling
- Regular regression tests
These components collectively represent a significant long-term commitment.
Timeline and resource commitment
To build and operationalize enterprise-grade SSO, organizations should plan for a sustained multi-quarter effort involving dedicated senior engineering resources. The table below provides a clear view of the effort and team size required:
Multi-tenant + org routing
Attribute and role mapping
Logging and support tools
Cert rotation + management
IdP testing and edge cases
Compliance review and audit prep
1 engineer + 1 compliance/ops
Support handoffs and debugging
Engineering + support team
Hidden operational burdens
Implementing SSO is not a "launch and forget" scenario. Teams often underestimate the ongoing operational responsibilities that pull resources away from core product development. The table below highlights these hidden yet significant recurring tasks:
Learn more : The Strategic Role of Authentication in B2B SaaS Applications
- SSO issues are hard to debug. Errors like "invalid assertion" or "clock skew" often reach engineering
- Your team becomes tier-1 support for IdP misconfigurations and login failures
2. Sales and onboarding delays
- SSO readiness is typically a deal blocker for enterprise customers. Delays in
SSO = delays in closing large deals
- Without a self-serve config UI, every new integration becomes a manual project
- Security reviews (SOC2, ISO, GDPR) will scrutinize your auth flows
- Incomplete validation of tokens, certs, or assertions can open up security holes
- Responsibility for audit trails, secure flows, and incident handling
- Each IdP (Okta, Entra, Google) behaves differently. Edge cases surface in production
- Testing both SP-initiated and IdP-initiated flows across providers requires dedicated QA and simulators
- SAML certs expire. Miss a renewal and customers can't log in
- Need tooling for monitoring, rotation, and error fallback
- OIDC and SAML specs evolve. Your libraries and flows must stay up-to-date
- Tech debt builds up fast without active maintenance
The case for rolling your own auth
Now that we've looked at what's required for building auth, we'll also briefly look at the benefits of rolling your own.
1. Control and customization
Without a doubt, rolling your own SSO solution offers complete control over the authentication process, allowing for customization that precisely fits your organization's specific needs. This is particularly important for unique or highly specialized use cases, where a custom SSO implementation might be the best approach.
2. Integration with legacy systems
For organizations with complex, legacy systems, a custom-built SSO might be necessary to ensure seamless integration that might not be possible with off-the-shelf solutions.
3. Long-term cost benefits
For large organizations with multiple product offerings, the initial high investment in rolling your own custom SSO might pay off over time. Depending on the size of your organization and the number of users, the cost of licensing third-party SSO solutions can be substantial depending on the vendor. Further, owning your infrastructure reduces dependency on a specific vendor’s technology, pricing changes, and terms of service. This can provide greater business continuity and stability.
Strategic alternative: Scalekit
Scalekit simplifies enterprise SSO by handling all the complexity and overhead for you. Here's what Scalekit offers out-of-the-box:
Enterprise SSO
Out-of-the-box support for both SAML 2.0 and OIDC protocols
SP and IdP-initiated flows
Handle both login types expected by enterprise customers
Multi-tenant architecture
Each customer can have their own SSO config without any custom code
Map user roles, departments, and other claims per customer
Works seamlessly with Okta, Microsoft Entra, Google Workspace, and more
Business velocity and customer onboarding
Out-of-the-box support for both SAML 2.0 and OIDC protocols
Handle both login types expected by enterprise customers
Each customer can have their own SSO config without any custom code
Security and compliance
Built-in validation, encryption, cert handling, and expiry checks.
Ready for SOC2, ISO, GDPR
Automated tooling to manage SAML cert expiry and updates
Developer experience
Dev, QA, UAT, and production environments included to map your SDLC lifecycle
Error diagnostics and logs
Real-time visibility into login errors, which means fewer escalations to engineering
We handle protocol changes, edge cases, and updates: so you don't have to.
ROI: Build in-house vs. Scalekit
Comparing strategic impact: Deciding whether to build or buy SSO comes down to understanding how each choice affects your business strategy, resource allocation, and speed-to-market. The following table compares critical factors of both approaches.
12–16 weeks of dedicated engineering effort
Go live in less than 3 days
2 backend, 1 frontend, 1 QA, 1 DevOps + ongoing
No dedicated engineering required
Must design and build admin interface from scratch
Self-serve portal ready out of the box
$100K–$120K in fully-loaded development costs
Free for first 3 connections. ~$3,000 annually for 10 connections
Permanent engineering allocation for maintenance, debugging, protocol updates, certificate management
Full operational responsibility included
Build vs. buy decision framework
This framework helps you determine whether to build internally or adopt a managed solution like Scalekit.
- Identity infrastructure is a core differentiator
- You have surplus engineering bandwidth
- Enterprise customer growth is not a priority
- You can commit to ongoing security ownership
- You want to close enterprise deals
- You want engineers focused on product innovation
- Operational simplicity is a priority
- You want to offer self-serve customer experience
Bottomline: Build or buy?
Scalekit provides enterprise-grade SSO without the heavy lifting, allowing your engineers to stay focused on product innovation:
- Complete SAML/OIDC implementation
- Support for multiple IdPs, accounting for the quirks of each
- Ready-to-deploy, secure, and compliant infrastructure
- Minimal operational overhead
- Fast deployment, freeing up your team
Choose Scalekit to simplify enterprise SSO, so your team can focus on what they do best.
Deciding whether to build or buy your SSO? Sign up for a Free Forever account with Scalekit and start with enterprise-ready SSO infrastructure instantly. Need help evaluating your options? Book time with our auth experts.
