Paris, Ile-de-France, France · Hybrid
$80k–$150k/yr
TLDR: We're looking for a Product Engineer (Backend – Rust) to own and evolve the core systems that power AI safety at scale – building APIs that handle hundreds of millions of requests, real-time policy enforcement, and…
Skills: Rust, Async Rust, Tokio, Axum, Actix
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Design and build high-throughput, low-latency backend services in Rust to power AI safety policies at scale. Own features end-to-end from API design and database schema to deployment and monitoring.
Requires professional experience shipping production backend systems in Rust, specifically using Tokio and web frameworks like Axum or Actix. Must have strong fundamentals in system design and proficiency with PostgreSQL.
TLDR: We're looking for a Product Engineer (Backend – Rust) to own and evolve the core systems that power AI safety at scale – building APIs that handle hundreds of millions of requests, real-time policy enforcement, and high-throughput data pipelines.
White Circle is an AI Safety company building the safety, reliability, and optimization layer for AI systems. At the core of our platform are policies – simple natural-language rules that define what an AI model should and shouldn’t do. We automatically test, enforce, and continuously improve these policies at scale.
We’ve raised $11M from top funds, founders, and senior leaders at OpenAI, Anthropic, HuggingFace, Mistral, DeepMind, Datadog, Sentry, and others
We process over one hundred million API calls every month
We fine-tune and train our own LLMs so they run faster and cheaper than any open or proprietary model
We’re a small, highly focused team. If you want to work deeply on hard problems, see your work ship to production quickly, and influence how AI safety is actually built – you’re the one we need.
Design and build backend services in Rust that handle real-time policy checks at scale – low latency, high reliability.
Own features end-to-end: from API design to database schema to deployment. You ship, you monitor, you iterate.
Work across the stack when needed – we care more about solving problems than role boundaries.
Improve system performance and reliability – connection pooling, caching strategies, query optimization, observability.
Collaborate directly with product, research, and ML teams to turn requirements into production systems.
You've built and shipped backend systems in Rust – not just tutorials, real production services.
You're comfortable with async Rust (Tokio), web frameworks (Axum, Actix), and database access patterns.
You have strong fundamentals in system design – you can reason about trade-offs, failure modes, and scaling.
You've worked with PostgreSQL and know how to write efficient queries, design schemas, and debug performance issues.
You communicate clearly and work well with others. Fluent English.
Experience with ClickHouse, Redis, or Kafka/event streaming
Kubernetes and infrastructure-as-code (Terraform, Helm)
Background in high-throughput systems monitoring systems, fintech
Salary of $80,000 to $150,000 + equity
Paid time off in line with your local regulations, no matter where you work from
Work from Paris (hybrid) + relocation package
Best medical insurance in France
All the hardware, tools, and services you need
Covered subscriptions for AI agents and IDEs
Team off-sites twice a year: we’ve recently been to the Alps and to Saint-Tropez
Intro call with one of our colleagues
Complete the take-home exercise
Show your best during the technical interview
Final call with our CEO and CTO
Please submit your application in English - it’s our company language so you’ll be speaking lots of it if you join
Runtime safety and alignment infrastructure for AI in the real world.
White Circle is the control layer for AI in production. We help companies test, protect, observe, and improve every AI interaction — from blocking unsafe inputs and preventing jailbreaks to analyzing user behavior and optimizing model performance.
View all jobs at White CircleRuntime safety and alignment infrastructure for AI in the real world.
White Circle is the control layer for AI in production. We help companies test, protect, observe, and improve every AI interaction — from blocking unsafe inputs and preventing jailbreaks to analyzing user behavior and optimizing model performance.
View all jobs at White Circle