Centene — .NET Modernization & DevSecOps at Enterprise Scale

01 The Challenge

Centene, one of the largest managed-care organizations in the United States, runs utilization management — the process that reviews and authorizes care — on a platform of desktop apps, web apps, Windows services, and state-specific health-plan modules, integrated with claims processing and EDI 834 enrollment feeds. Much of it stood on .NET Core 3.1, past end-of-life, spread across hundreds of repositories owned by many teams.

The platform needed three things at once: a coordinated move to .NET 8, a serious upgrade to its container and pipeline security posture, and a path to AWS — all without interrupting the healthcare operations running on it every day.

02 The Approach

Modernization at that scale is a coordination problem before it is a code problem. Leopard Data authored the .NET 8 upgrade playbook on Confluence that teams across the organization followed, and backed it with an application inventory swept across hundreds of repositories — framework versions, output types, and upgrade order — so architects were planning from facts. We then upgraded the shared common libraries first (authentication, messaging, caching), the foundation every other team’s upgrade depended on, and proved the pattern by personally carrying more than fifteen services through upgrade, Dockerfile, pipeline, and scan — including seven stories moved to QA in a single day.

The pipeline work turned modernization into a security upgrade too: GitLab CI/CD deployment pipelines extended to three new environments, Enterprise SonarQube and Prisma container scanning integrated into the templates, and a CyberArk + Conjur secrets-management design that took credentials out of pipeline configuration and put them under vault control. Observability came along for the ride — Serilog and OpenTelemetry middleware in the reference API, wired to Splunk and Dynatrace.

03 The Delivery

The influence grew with the results. Leopard Data joined other teams’ stand-ups to guide their upgrades, fielded questions from at least four other teams, and drove multi-hour working sessions from a shared screen. We ran the container-image vulnerability remediation program end to end — inventory, prioritized batches, coordinated team-wide execution — and presented the approach to senior leadership. We also migrated legacy state health-plan modules onto the modern core platform, resolving hundreds of compatibility issues along the way.

A month into the engagement, the client named Leopard Data’s principal lead of the platform’s AWS lift-and-shift migration; before contract end, leadership asked him to take the lead SRE role for the following year and raised converting the engagement to a permanent position — the kind of signals that say more than any self-assessment could.

05 Tech Stack