Engagement type: Freelance / Contract Duration: Initial 3–6 months (extension possible) Location: Remote Start: ASAP Project overview We are looking for a senior, hands-on systems engineer to help design and build high-scale automation and simulation systems for transaction-heavy digital procurement workflows (simulated buying). The core challenge is building distributed, resilient systems that can orchestrate large numbers of concurrent, human-like actors interacting with well-known web-based platforms in a realistic and reliable way. This role is engineering-heavy and suited for someone who enjoys solving hard problems around scale, concurrency, reliability, and system behavior modeling. What you’ll be working on Designing and implementing distributed automation / simulation architectures Orchestrating thousands of concurrent browser or API-based workflows Building systems that model realistic user behavior patterns (timing, sequencing, variability) Managing session state, retries, failures, and partial success scenarios Implementing observability: logging, metrics, error tracking Collaborating on architecture decisions and trade-offs (latency vs reliability, cost vs scale) Required experience 5+ years of senior backend / systems engineering experience Strong hands-on experience with Python (async), Go, or Node.js Experience building high-concurrency, distributed systems Solid understanding of: Async processing Queues / workers (e.g. SQS, Kafka, Redis) State management at scale Experience with browser automation frameworks (e.g. Playwright, Puppeteer) or complex API-driven workflows Strong debugging and problem-solving skills under real-world constraints Background in one or more of: Trading systems Marketplaces AdTech / Fraud systems Load testing or simulation platforms Gaming or anti-cheat systems Familiarity with behavioral modeling or synthetic user generation Strong opinions on system design — and the ability to defend them What this is not Not a simple scraping task Not a junior automation role Not a basic CRUD application This is a senior engineering role requiring architectural thinking and production-grade implementation. Engagement details How to apply Please include: A short description of similar systems you’ve built (focus on scale & complexity) We need a full CV, without a CV your application will be rejected Your preferred tech stack Any relevant GitHub or project references (if shareable) Contracting: You will be contracting with the client directly, and we will take a one-time introduction fee, but will not be responsible for any tasks or development efforts