David Kalinowski

Led secure backend development using C# (.NET Core, ASP.NET) and Python (FastAPI) to process sensitive healthcare data with HIPAA-compliant storage and fast API performance. Built patient dashboards and mobile wellness features with React, Next.js, and React Native, optimizing cross-platform usability. Delivered accessible UI components with MUI and React Native Paper. Implemented JWT and OAuth2 authentication with RBAC across dashboards, APIs, and mobile apps. Integrated OpenAI and third-party ML APIs to deliver health insights and patient support. Designed REST and GraphQL APIs with strict validation and versioning, and used Entity Framework Core with PostgreSQL to model patient records and permissions. Reduced backend latency by 40% via async queues (Hangfire, Celery), Redis caching, and bottleneck refactoring. Architected schemas in PostgreSQL and MongoDB for structured and unstructured data; deployed .NET Core microservices on Azure with Docker, Functions, Blob Storage, and API Ma

Senior Software Engineer building secure backend services in Nest.js and FastAPI for HIPAA-compliant healthcare data processing; developed patient dashboards and cross-platform wellness features using React, Next.js, and React Native; implemented a streaming chat UI and secure JWT/OAuth2 with RBAC; shipped an LLM-powered symptom checker (OpenAI + LangChain, RAG) to reduce triage time; designed REST and GraphQL APIs with clear versioning; modeled data with TypeORM and SQLAlchemy across PostgreSQL and MongoDB; optimized prompts, caching, and batching to reduce monthly token spend by ~25%; improved backend performance via async queues and Redis; deployed services on AWS and Azure; automated tests and deployments with GitHub Actions and Terraform; led cross-functional sprints and mentoring.

Built secure backend services in Nest.js and Python (FastAPI) to process sensitive healthcare data with HIPAA-compliant storage and fast API performance. Developed patient dashboards and mobile wellness features using React, Next.js, and React Native; implemented streaming chat UI; established secure JWT/OAuth2 authentication with RBAC for dashboards, APIs, and mobile platforms. Shipped an LLM-powered symptom checker (OpenAI + LangChain, RAG on clinical notes) reducing triage time. Designed REST and GraphQL APIs, modeled patient records and permissions in PostgreSQL and MongoDB, and optimized prompts and caching to reduce monthly token spend. Improved backend response time by 40% with async queues and Redis. Architected schemas for structured/unstructured medical data and deployed services on AWS/Azure with Docker, S3, and Lambda. Set up GitHub Actions and Terraform pipelines and led cross-functional sprints.