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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