●TypeScript + SaaS

Legacy migration succeeds or fails based on risk management, not technical excellence. The most elegant new architecture is worthless if the migration never completes. The strangler fig pattern—incremental replacement of legacy capabilities—succeeds because it delivers continuous value while managing risk. An API gateway sits in front of both systems, routing requests to old or new implementations based on feature flags. Each migrated capability goes through phases: shadow mode, comparison mode, gradual rollout, and finally retirement of old capability. This pattern means the migration can pause or rollback at any point without disaster. Data synchronization is often the hardest challenge. Change data capture can keep databases synchronized without modifying legacy code, enabling incremental migration while both systems see current data.

Legacy migration engagements start with archaeology: understanding the existing system deeply before proposing changes. This means code review, database analysis, and conversations with people who've worked with the system for years. Migration strategy design identifies which capabilities migrate first, what dependencies exist, and where natural seams allow incremental extraction. The strategy produces a phased plan where each phase delivers standalone value. The facade architecture enables incremental migration. I help design the routing layer and feature flag infrastructure. Monitoring compares outputs, catching discrepancies before they affect users. Each phase follows a consistent pattern: build, deploy in shadow mode, compare exhaustively, gradually shift traffic, complete cutover, decommission old code.