About the role
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.
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Compensation: $80K – $150K • Higher figures and equity are negotiable
* • $80K – $150K • Higher figures and equity are negotiable
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