Product Engineer (Backend)

Npv; Paris; Hybrid; EUR 71,000 - 134,000; Full time

Benefits offered by this job

Visa sponsorship

Relocation assistance

Job summary

White Circle is seeking a Product Engineer, Backend (Rust) to design and scale real-time policy checks within a cutting-edge AI safety platform. You’ll own Rust services end-to-end, from API design and schema to deployment and observability.

The role demands production Rust (Tokio), PostgreSQL, and async design, plus strong system-design skills. Hybrid relocation to Paris or London with visa support is provided.

Qualifications

• Production experience with Rust, Python, or Go.
• Comfortable with async Rust (Tokio).
• Experience with Axum/Actix and PostgreSQL.
• Strong system design fundamentals.

Responsibilities

• 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 caching, pooling, and observability.
• Collaborate with product and research.

Skills

Rust

Python

Go

Async Rust

System design

Tools

Tokio

Axum

Actix

PostgreSQL

Job description

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.

Responsibilities

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.

Bonus

• ClickHouse, Redis, Kafka, LLM infra (routing, inference, RAG), or high-throughput monitoring background.

Benefits & Compensation

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