Caleb Ulffers

I’m a backend architect with 9 years of experience building resilient systems that handle high-stakes financial and healthcare data. I’m driven by the gritty performance bottlenecks—finding and fixing the root causes that keep platforms from scaling.

At Upward, I built microservices infrastructure using Java for transactional integrity and Go for API gateways, maintaining uptime while moving 150 million dollars in annual GMV. I investigated and resolved an API freeze caused by an AccessExclusive lock collision during schema migrations by implementing lock timeouts and splitting DDL transactions to keep the write path open. I also created a fraud detection engine with Python and Apache Kafka that processes 10,000 events per second with latency under 100 milliseconds.

Previously at Xealth, I refactored an HL7 ingestion pipeline from Java to Rust (Tokio runtime), eliminating segmentation faults and reducing heap usage by 72% across 500 clinical facilities. I designed sub-second medical record search with Elasticsearch and FastAPI, standardized EHR data stream handlers for identity resolution, and automated HIPAA-compliant Kubernetes CI/CD to increase release cycles by 50%. Before that, at Peak6, I built a risk assessment and automated capital allocation engine for a market-neutral platform managing 50 million dollars in assets and improved PostgreSQL performance by 40% through partitioning.