Backend Engineer - Europe/UK Timezone

Backend engineer at PostHog building high-throughput low-latency feature flag evaluation services using Rust and Python. Work autonomously in a European timezone on critical infrastructure that millions of requests per minute depend on.

• Build and own the feature flag tools, SDKs, evaluation services, and in-app UI
• Own whole services end-to-end, including reliability, stability, and performance of targeting service and local evaluation endpoints
• Implement real-time cohorts for instant membership evaluation
• Move from read-heavy to write-heavy architecture with dedicated store for flag evaluation
• Develop an AI-first flag management tool
• Lower p50/p90/p99 latencies and isolate evaluation path from upstream failures

• Experience building and operating high-volume systems (millions+ requests per minute) with care for tail latency, caching, and distributed systems failure modes
• Productivity in Rust and Python (or confidence to learn quickly)
• Ability to work independently and ship fast without breaking services
• Based in a European time zone
• Nice to have: experience with feature flags, customer data platforms, real-time decision engines, incident response, cloud infrastructure, benchmarking/profiling tools