Trust as Productive Infrastructure: Plaid, Passkeys, Identity

The client is the leading HSA and health-finance custodial administration platform with millions of HSAs and total accounts, and tens of billions in HSA assets. The business generates over a billion dollars in annual revenue at strong EBITDA margins. Taller's engagement at this client is one of the broadest multi-pod engineering footprints in the portfolio outside the global payments company organization. The three cases below describe what Taller has built or contributed to across the multi-tenant cloud modernization, the integration substrate for vendor-provided trust capabilities (Plaid, passkeys), and the team's same-client AI tooling work.

The HSA platform company's anti-fraud and identity strategy requires integrating Plaid for instant identity-and-bank verification and passkeys for passwordless authentication into the legacy ASP.NET MVC estate, without breaking the existing fraud-API testing pipeline or the operational discipline around custodial accounting. Vendor capabilities have to be wired through integration code that can be called from legacy ASPX applications, and passkey enrollment loops have to handle credential fallback without confusing members.

Taller operates the Plaid integration pod with dedicated Frontend, Backend, and QA engineering against Plaid's anti-fraud measures inside the ASP.NET MVC platform. The work covers new MS Test framework cases for the fraud APIs, contracts callable from legacy ASPX applications, and UX paths that handle Plaid's instant-verification outcomes alongside the manual microdeposit fallback. The Identity team contributes scalable identity services for authentication and authorization: passwordless authentication, multi-factor authentication, and passkeys, generating C# and Node.js code with Copilot-assisted tooling. The broader anti-fraud and anomaly-detection capability Taller carries is anchored elsewhere through the cybersecurity company's real-time anomaly and threat detection engagement (Python and ML models against multi-source endpoint telemetry), serving as the capability reference for the regulated-fraud posture.

Sustained Plaid integration pod presence across Frontend, Backend, and QA functions, delivering integrations with Plaid's Identity, Auth, and Signal APIs and enabling seamless frontend experiences through Plaid-provided components. The resulting workflow replaced legacy micro-deposit verification with near-real-time identity validation and instant bank account confirmation, significantly reducing onboarding friction and improving the member experience.

Taller also maintained a dedicated Identity engineering pod with Lead and Senior-level engineers focused on passkeys, passwordless authentication, and modern identity capabilities. Combined with AI-assisted development practices using GitHub Copilot, these initiatives accelerated delivery while strengthening both security and usability across the platform.

The HSA platform company's trust outcomes are significant: 3.5 million passkey registrations, a ninety-eight percent reduction in erroneous declines of legitimate transactions, fraud rates approximately eighty percent below industry peers, and a seventy percent quarter-over-quarter reduction in fraud-related service costs following Plaid deployment. These are the result of the HSA platform company's product strategy, Plaid's anti-fraud capabilities, and the platform's broader identity and security posture.

The modernization of account and identity verification workflows delivered meaningful operational and customer-experience improvements. By replacing traditional micro-deposit verification processes with instant bank authentication, account verification times were reduced from several days to as little as ten seconds. This eliminated a major source of onboarding friction, reduced member-service call volume, and contributed to higher customer satisfaction and faster access to platform services.

The integration substrate that enables vendor capabilities (Plaid identity verification, passkeys, and WebAuthn standards) to operate within a highly regulated financial platform without disrupting custodial accounting is where Taller's Integration and Identity engineering pods contributed. Their work ensured that modern identity and fraud-prevention capabilities could be adopted while maintaining the reliability, compliance, and operational integrity required by the business.