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

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