AI engineer for subscription products

Ruby Labs is a leading tech company that creates and operates innovative consumer products. We offer a diverse range of opportunities across the health, education, and entertainment industries. Our innovative teams are driving the future of consumer-led products, and we're always looking for passionate individuals to join us. We are looking for a Senior AI Engineer to own and scale the AI layer of one of our core D2C subscription products.

• Design dynamic prompt templates with conditional logic and context injection that maximise generation quality
• Enforce predictable outputs with JSON mode, function calling, Zod/JSON schemas, validators, and repair loops
• Own complex LLM workflows (LangChain, LlamaIndex, or custom) that integrate cleanly into application logic
• Build and maintain browser automation on Browserbase Functions and Playwright that traverses web flows reliably
• Classify screens with a model inside each traversal, and decide what the model handles versus deterministic code
• Ship automations as frozen, published workers — versioned, reproducible, and safe to roll back
• Orchestrate runs through Hatchet with retries, timeouts, and failure traces that explain every broken run
• Build evaluation pipelines — test datasets, LLM-as-a-judge, RAGAS-style metrics — and score responses and screen classifications in Langfuse
• Trace complex LLM chains to find bottlenecks in cost, latency, and context-window usage
• Run A/B experiments across models and prompts through an AI gateway (OpenRouter, Cloudflare AI Gateway); release only on quantitative benchmarks
• Re-evaluate models as new architectures emerge; fine-tune when domain requirements demand it
• Take AI features from experiment to live production on Cloudflare Workers and Containers, and stay accountable after release
• Manage rate limits, fallbacks, and model cost so features stay reliable at scale
• Resolve production incidents in owned AI and automation systems with documented root-cause analysis

• 5+ years of software engineering with Node.js, TypeScript, Next.js, and Postgres, including edge or serverless runtimes such as Cloudflare Workers
• Production browser automation with Playwright (Browserbase or similar): resilient selectors, retries, failure handling at scale
• Production experience with dynamic prompting — content that depends on input variables and injected context
• Structured outputs in production: JSON mode, function calling, Zod/JSON schemas
• Experience with unified LLM APIs or AI gateways (OpenRouter, Cloudflare AI Gateway): rate limits, fallbacks, cost-effective model selection
• LLM observability with Langfuse or similar: tracing, test datasets, scoring integration
• Evaluation methodology: RAGAS or custom LLM-as-a-judge systems
• Decides on benchmarks and trace data, not intuition
• Analytical — converts generation logs into metrics a business can act on
• Iterative — builds feedback loops and improves continuously
• Owns the outcome from experiment to production, and after
• Verifies before trusting — treats LLM output as unproven until validated
• Applicants from any country are welcome to apply for the position as long as they are located within approximately ± 4 hours of CET.

• Remote Work Environment: Embrace the freedom to work from anywhere, anytime, promoting a healthy work-life balance.
• Unlimited PTO: Enjoy unlimited paid time off to recharge and prioritize your well-being, without counting days.
• Paid National Holidays: Celebrate and relax on national holidays with paid time off to unwind and recharge.
• Company-provided MacBook: Experience seamless productivity with top-notch Apple MacBooks provided to all employees who need them.
• Flexible Independent Contractor Agreement: Unlock the benefits of flexibility, autonomy, and entrepreneurial opportunities. Benefit from tax advantages, networking opportunities, reduced employment obligations, and the freedom to work from anywhere.