Oleg Mihajlov

Key backend engineer building the anti-fraud rules platform from an early-stage prototype to production readiness, owning critical subsystems. Cut hot-path p99 latency by 37% through rule execution deduplication, compilation caching, and query parallelization — optimizations that also halved monthly database costs. Architected and led the migration to an in-app authentication and user management system, replacing the legacy auth flow, and mentored mid-level engineers joining the team.

Returning intern on the Observability team, building tooling on Stripe's company-wide metrics platform across the full stack — stream processing in Java/RxJava on Netflix Mantis, a React frontend, and Terraform infra over Prometheus and AWS. Built a self-service tool that lets on-call engineers pull detailed info for any metric on demand, surfacing which subsets of machines are degraded during an incident instead of digging through logs. Piloted it with 2 engineering teams against live incidents.

First internship on Stripe's Observability team, building cost-attribution tooling for the company's Prometheus platform. Built a self-service tool that attributed each team's Prometheus metrics and exposed their cost in a UI, so teams could prune their own expensive, high-cardinality metrics instead of the observability team manually hunting them down and chasing each owner. Adopted across teams and driving recurring annual cloud savings — realized before the internship even ended.

Improved the Podcast Episode page with data-driven design changes — 4.3% increase in user retention and 15% boost in engagement within 3 months. Cleaned up 4,000+ lines of obsolete code and brought test coverage above 90%.