8 Hidden Costs of Building In-House SSO Infrastructure

Building a Single Sign-On (SSO) system in-house presents significant hidden costs and challenges that are often underestimated by engineering leaders. While the initial estimate for such a project may appear straightforward, the true three-year cost can range from $700,000 to $2 million, factoring in the intricacies of identity provider (IdP) quirks, protocol updates, compliance requirements, customer support, and potential security incidents. These hidden expenses are categorized into eight areas, including IdP quirks, protocol churn, and audit log infrastructure, among others. The decision to build vs. buy is frequently mispriced, as the total cost of ownership (TCO) is typically three to five times higher than initial projections. For most B2B SaaS companies, buying a managed SSO platform often proves more cost-effective, especially if onboarding multiple enterprise customers is anticipated, as buying can pay for itself within the first year. Managed solutions like SSOJet can mitigate these hidden costs by providing pre-built connectors, automatic protocol updates, and handling security responses, thus allowing engineering teams to focus on core product development rather than ongoing identity management burdens.