API Authorization Decisions Slowing Financial Platform Access

Your team operates a cross-border payments platform processing billions in annual volume for enterprise customers and financial institutions. The platform exposes APIs consumed by three distinct caller types: end-user web clients, internal customer service staff authenticated via an enterprise IdP, and machine-to-machine service integrations from external partners. As the tenant count grows past several dozen organizations, each with distinct role hierarchies and data isolation requirements, your access control layer is showing strain. Authorization logic is scattered across application code, Lambda functions, and hand-rolled policy evaluations. Compliance audits are increasingly painful because policy changes leave no centralized trail. Several tenants have escalated incidents where users accessed data outside their organizational boundary. Your security team can no longer attest to consistent policy enforcement across user types, and onboarding a new tenant requires bespoke engineering work estimated at several sprint cycles.