Multi-Tenant Cloud Platform Modernization

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 HSA platform, a monolithic ASP.NET MVC and SQL Server estate, needed to dissolve into a microservices architecture without breaking the regulatory boundary around custodial accounting. Each microservice that touches money has to defer to the same source-of-truth ledger, or reconciliation defects compound. The same constraint applies as the legacy SOAP and WCF estate is gradually replaced with REST services integrating into the Supply Chain Management systems.

Taller engineers contribute to the multi-pod modernization across multiple product surfaces. The investment-management features build (automated investment contributions, portfolio rebalancing, curated mutual fund options, streamlined tax preparation) was delivered alongside the HSA platform company on the ASP.NET MVC + SQL Server + AngularJS → Angular 9 + C# stack as part of the broader monolith-to-microservices migration. The 2024-2026 work spans the New API pod migrating legacy SOAP and WCF services to REST on .NET Core with OpenAPI specifications and REST adapter layers integrated into the SCM systems; Azure platform engineering on App Service, AKS, Service Bus, Application Insights, Application Gateway, Cache for Redis, Event Grid, Key Vault, and Azure SQL with cost optimization and self-healing automation; Azure Databricks plus dbt plus PySpark data engineering; and Plotly Dash BI delivery. Leadership-tier roles — Scrum Masters, Technical Program Managers, Microsoft Practice Leaders — embed across the engagement.

The investment-management initiatives delivered enhanced portfolio management capabilities and a significantly improved member experience, with streamlined tax preparation emerging as a key business outcome. As part of this effort, the team re-engineered both the desktop platform and mobile application into a unified, intuitive investment workspace that consolidated automated document processing, real-time portfolio performance tracking, and automated asset-reallocation capabilities within a single secure dashboard.

These improvements simplified complex financial workflows for members while increasing operational efficiency and transparency. In parallel, Taller maintained a sustained multi-pod engineering presence from 2023 through 2026 across Identity, API modernization (SOAP-to-REST), Plaid integrations, Azure platform engineering, and BI/Data Engineering functions, providing the technical foundation required to support ongoing product evolution.

The HSA platform company's outcomes from the multi-year platform modernization are significant: a significant service-cost reduction, five percent lower total cost of revenue, nine percent revenue growth, and strong adjusted EBITDA margins (up from the prior period). These are enterprise outcomes earned by the platform's overall architectural strategy and the full multi-year program. The architectural strategy is the HSA platform company-defined. Taller's contribution is the engineering execution across the investment-management features build and the multi-pod modernization activity sitting underneath the broader transformation.