Sarah Kowalski
Full-Stack Software Engineer
5 years exp.
Go · Rust · TypeScript
Experience
ShopifySep 2022 — Present
Backend Engineer, Checkout Infrastructure · Remote
- Scaled checkout API from 2M to 10M req/day with zero downtime during Black Friday peaks — 99.99% uptime.
- Rewrote payment session state machine in Go, cutting p99 latency from 340ms to 82ms.
- Led migration from monolith to gRPC microservices for 3 services, reducing deploy cycle from 2h to 12min.
- On-call rotation lead for 8 engineers; authored 4 incident postmortems preventing recurrence.
N26Jul 2019 — Aug 2022
Software Engineer, Data Platform · Berlin
- Built real-time transaction streaming pipeline processing 15M events/day using Go, Kafka, and ClickHouse.
- Designed fraud detection feature store serving 200+ ML features at <5ms p99 latency.
- Wrote internal CLI tooling used by 80 engineers daily for database migrations and service scaffolding.
Open Source & Projects
OpenCache
github.com/sarahk/opencache · 2.4k ⭐
High-performance distributed caching library for Go with LRU, LFU, and TTL eviction policies. Featured in Go Weekly.
querycraft.dev
querycraft.dev
AI-powered SQL query generator with schema introspection. Rust + WASM backend, SvelteKit frontend. 800 MAU.
rust-bench
github.com/sarahk/rust-bench · 1.1k ⭐
Micro-benchmarking framework for Rust with flamegraph integration and CI reporting. Used by 40+ Rust OSS projects.
Speaking
GopherCon Berlin 20242024
Profiling Go Services in Production Without the Overhead
Rustconf 20232023
Writing Zero-Copy Parsers in Rust: Lessons from Production