Zachary Johnson

Remote Senior Software Engineer at Optum

Architected a unified care coordination platform enabling seamless scheduling, dispatch, and tracking for non-emergency medical transportation; ensured interoperability with HL7/FHIR standards using C#, ASP.NET Core, Angular 14, and Azure AI services. Built real-time claims and billing workflows, exposed REST and gRPC endpoints for partners, and integrated Azure Service Bus for automated event-driven notifications. Optimized SQL Server data models and EF Core queries for RPM and NEMT workloads; modernized patient and caregiver portals by migrating AngularJS to Angular 14 with RxJS caching and Kendo UI. Implemented real-time alerts via SignalR; secured PHI with Azure Key Vault and OAuth 2.0/JWT; centralized API access with API Management and Application Gateway; orchestrated containers on AKS; established rate limits and quotas. Standardized CI/CD with Git and Azure DevOps; automated testing and blue/green rollouts; mentored junior engineers and led code reviews.

Senior Software Engineer at Keysight Technologies

Shipped versioned ASP.NET Core APIs (REST and gRPC) with OpenAPI/Protobuf contracts and NSwag-generated SDKs; enforced schema governance and contract testing. Rebuilt clinical and lab platforms into secure, web-first systems using AWS-hosted microservices and HIPAA HL7/FHIR mappings. Built clinician portals with Blazor, Telerik/Kendo components, EF Core/LINQ; implemented RBAC/OIDC/OAuth; operated APIs behind API Gateway with staged canaries; ran workloads on Lambda/ECS and instrumented via CloudWatch/OpenTelemetry. Built Angular 8 clinician portals with TypeScript, RxJS, NgRx; defined domain-aligned microservices topology using DDD, RabbitMQ, AWS SQS/SNS, and Redis caching for access, authorization, and reporting. Delivered high-volume data-rich UIs (Kendo Grid/Scheduler) with Kendo; ensured HIPAA-aligned security and audit trails.

Junior Software Engineer at Citigroup

Maintained and modernized financial transaction and client management web apps; migrated legacy document tool to ASP.NET MVC; enhanced investor enrollment modules with React/TypeScript, Material UI; created SSIS/ETL pipelines to transfer data to analytics warehouse; implemented near real-time updates with Azure Functions and Data Factory; ensured regulatory compliance and reliability.

Sr. Software Engineer at KeySight Technologies

Rebuilt clinical and lab platforms into web-first systems using AWS microservices and HIPAA/Hl7/FHIR standards; migrated WPF tools to ASP.NET Core MVC; shipped versioned REST/gRPC APIs; built clinician portals with Blazor and Kendo; ran workloads on Lambda/ECS via API Gateway; implemented Angular 8 clinician portals with RxJS/NgRx; defined domain-aligned microservices topology using DDD, RabbitMQ and AWS SQS/SNS; delivered RBAC-enabled UIs with OIDC/OAuth; supported SAFe and trunk-based development; emphasized HIPAA-compliant access controls with AWS KMS and HL7/FHIR mappings.