John Angelo Santos

I’m a Senior Software Engineer with 13+ years of experience building distributed backend systems, retrieval-based AI search platforms, and cloud-native services across enterprise and government environments. I’m focused on Python and Java backend engineering, with additional experience in C# and TypeScript, and I care deeply about backend scalability, search/retrieval performance, and secure data access in distributed systems.

At Microsoft, I build and maintain enterprise AI search and Microsoft 365 Copilot-related services, contributing to retrieval systems, secure data access, and backend performance. I’ve supported hybrid retrieval architectures (BM25 + vector similarity) with Azure AI Search, optimized production query paths, and improved query latency from ~500ms to sub-200ms under real traffic by refining indexing strategy and execution flow. I also design RAG pipeline components (ingestion, chunking, embeddings, ranking, response assembly with traceable outputs) and implement permission-aware retrieval logic to enforce user-level access control across enterprise data sources.

Previously, I worked on large-scale Irish government systems—building Java Spring Boot services for national payroll submission processing and Python services for entity matching and identity reconciliation across agency datasets. I improved matching accuracy to ~98% through iterative tuning and validation, and I helped address production data consistency and high-volume transactional reliability challenges. I thrive where correctness, observability, and secure, high-performance backend engineering matter.