Start by inventorying which applications depend on each identity provider, then rank those dependencies by business criticality and migration complexity. Keep legacy and modern providers in a controlled coexistence state only as long as needed, with clear retirement criteria. The goal is to reduce trust complexity without forcing a cutover that creates new access failures.
Why This Matters for Security Teams
Rationalising identity providers is not just an infrastructure cleanup exercise. It changes how applications authenticate, how tokens are issued, and where trust is anchored. If that work is done too quickly, teams can break SSO flows, invalidate service-to-service trust, or strand legacy apps that still depend on older protocols. NIST’s Cybersecurity Framework 2.0 frames this as a resilience problem as much as an access problem: reduce complexity, but preserve continuity.
The real risk is hidden dependency. One provider may still support partner portals, machine-to-machine integrations, or admin workflows that never made it into the formal inventory. NHIMG’s Ultimate Guide to NHIs notes that NHIs outnumber human identities by 25x to 50x in modern enterprises, which means identity sprawl is usually wider than teams expect. In practice, many security teams encounter authentication outages only after an application owner has already changed a trust assumption without realising how many downstream systems depended on it.
How It Works in Practice
The safest path is to treat identity-provider rationalisation as a dependency mapping programme, not a cutover project. Start by building an inventory of every application, API, service account, and integration tied to each provider. Then classify those dependencies by protocol, criticality, user population, and migration complexity. This is where NHI governance matters: many of the hardest breakages come from secrets, service accounts, and automated jobs rather than from interactive login flows.
Current best practice is to keep both providers in controlled coexistence while you migrate workloads in waves. That means:
- Preserving existing token formats and claims where applications depend on them.
- Using federation or trust bridges for interim interoperability, rather than forcing immediate reconfiguration.
- Setting explicit retirement criteria for each legacy dependency so coexistence does not become permanent.
- Testing service accounts, API keys, and automation separately from human SSO flows.
For NHI-heavy estates, the operational concern is often not the login page but the workload identity behind it. NHIMG’s Top 10 NHI Issues and the 52 NHI Breaches Analysis both reinforce the same pattern: weak visibility into non-human access leads to overlong trust relationships that survive provider changes. That is why teams should pair provider consolidation with secret rotation, entitlement review, and offboarding for any credentials tied to the retired IdP. These controls tend to break down in highly distributed environments where application owners can create shadow dependencies faster than central identity teams can validate them.
Common Variations and Edge Cases
Tighter identity consolidation often increases migration overhead, requiring organisations to balance reduced trust sprawl against application stability. That tradeoff becomes sharper when the estate includes SaaS products, partner integrations, old SAML implementations, or systems that cannot support modern federation standards. There is no universal standard for how many identity providers is “too many”; current guidance suggests focusing on actual dependency risk rather than arbitrary platform count.
Some applications can move cleanly to a single provider, while others may need long-lived coexistence because of contractual constraints, embedded device authentication, or vendor lock-in. In those cases, the goal is not immediate uniformity but controlled divergence: keep the legacy IdP only for named exceptions, monitor those exceptions closely, and require a dated exit plan. If the environment includes large volumes of NHI traffic, the retirement plan should include machine identities as first-class citizens, not an afterthought.
Rationalisation also becomes harder when claims mapping differs across providers. A migration may appear successful for human users while silently breaking downstream authorisation logic that depends on group claims, roles, or tenant-specific attributes. That is why a pilot group and parallel-run period are usually safer than a big-bang cutover.
Standards & Framework Alignment
This section maps relevant standards and security frameworks to the operational risks and controls described in this guidance.
OWASP Non-Human Identity Top 10 address the attack and risk surface, while NIST CSF 2.0 and NIST AI RMF set the governance and control requirements practitioners need to meet.
| Framework | Control / Reference | Relevance |
|---|---|---|
| NIST CSF 2.0 | PR.AC-4 | Identity provider rationalisation changes how access is granted and enforced. |
| OWASP Non-Human Identity Top 10 | NHI-01 | Multiple IdPs often hide service account and secrets sprawl across apps. |
| NIST AI RMF | Rationalisation is a governance and risk decision across changing trust relationships. |
Treat IdP consolidation as a managed risk change with clear ownership, validation, and rollback paths.
Related resources from NHI Mgmt Group
- How should organisations centralise password management without breaking legacy applications?
- How can organisations tell whether their current identity model still fits platform change?
- How should fintech teams centralize authorization across multiple applications?
- When should organisations prioritise browser security over other identity controls?
