Financial services · Greylock Capital Services
Fintech Platform Rebuild: -78% P1 Incidents
Rebuilt a critical trade-lifecycle platform from a monolithic Java codebase into a service-oriented architecture with strong observability and a real testing strategy.
Problem
A 12-year-old Java monolith processed $2.4B in daily trade volume. It was suffering a P1 incident roughly every 10 days, and no engineer on the team fully understood the deployment. Adding a new field to a form took an average of nine engineering days.
Solution
We ran a three-month strangler-pattern migration: identified the four highest-risk seams, extracted them into typed TypeScript services behind a stable API layer, added contract tests between the old and new sides, and cut over module by module. We paired every migration with observability so we could see the blast radius before it hit customers.
Result
P1 incidents dropped 78% year-over-year. The team now ships new form fields in under a day. The migration finished on time and on budget. The last-mile Java modules are on a documented sunset plan the client's own engineers own.