Distributed Systems Engineer

Work on Windmill's Rust backend - the execution engine, workers, language runtimes, API layer, and infrastructure that powers thousands of production deployments. Execution engine : scheduling, job queues, worker orchestration, flow execution with branching, parallelism, retries, and error handling. Language runtimes : maintain and extend sandboxed runtimes for Python, TypeScript, Go, Bash, SQL, and more. Performance & reliability : profiling, optimization, resource management. Our users run mission-critical workloads - correctness and uptime matter. Infrastructure : PostgreSQL schema design, caching, networking, deployment tooling. Who we're looking for This is a senior role. We're looking for someone who has operated distributed systems at scale and can teach us from day one - showing us PostgreSQL patterns, distributed systems techniques, and architectural improvements we haven't considered yet. Proven experience building and operating distributed systems at scale - not theoretical, you've done it in production Deep PostgreSQL expertise - query optimization, schema design, concurrency control, partitioning, replication. You know what breaks at scale and how to fix it. Strong systems programming skills - Rust experience strongly preferred, otherwise C/C++ with willingness to switch You bring opinions and techniques from previous infrastructure work that will make Windmill better immediately You enjoy hard infrastructure problems and care about correctness Example projects in your first 3 months Redesign the job queue to handle bursty workloads with thousands of concurrent jobs without degrading scheduling latency Implement a new worker orchestration strategy that improves resource utilization across heterogeneous deployments (2 to 600 workers) Optimize critical PostgreSQL queries and schema for customers with millions of completed jobs - partitioning, indexing, vacuum tuning Add a new language runtime (e.g., Java, C#) with proper sandboxing, dependency management, and execution feedback Build observability tooling - distributed tracing across the flow execution engine to diagnose slow or failing steps in production Offer details Location : Paris hybrid (\~3 days/week) or remote within France Contract : Full-time / CDI Salary : €60K–€90K gross + top of market for level + 20% bonus on collective milestones