Product Engineer (Backend)

We're looking for a Product Engineer, Backend (Rust) to join White Circle, an AI Safety company building the safety, reliability, and optimization layer for AI systems through natural-language policies it automatically tests, enforces, and improves at scale. Backed by $70M (Series A) from top funds and senior leaders at OpenAI, Anthropic, HuggingFace, Mistral, DeepMind, and others, White Circle processes 100M+ API calls monthly and fine-tunes and trains its own LLMs to run faster and cheaper than open or proprietary models. You will - Design and build Rust backend services handling real-time policy checks at scale. - Own features end-to-end – API design, schema, deployment, monitoring. - Improve performance and reliability through connection pooling, caching, query optimization, and observability. - Collaborate directly with product and research. Requirements - Production experience with Rust, Python, or Go. - Comfortable with async Rust (Tokio), Axum/Actix, and PostgreSQL – schema design, query optimization, debugging. - Strong system design fundamentals: trade-offs, failure modes, scaling. - Relocation to Paris or London (hybrid) required. Stack - Rust, Tokio, Axum/Actix, PostgreSQL. - Bonus: ClickHouse, Redis, Kafka, LLM infra (routing, inference, RAG), or high-throughput monitoring background. We offer - $80k–$150k/year salary + equity; higher figures can be negotiated. - Official employment, visa and relocation help. Compensation: $80K – $150K • Higher figures and equity are negotiable - • $80K – $150K • Higher figures and equity are negotiable Find Jobs in France on Arbeitnow