Senior AI Engineer

Ruby Labs is a leading tech company that creates and operates innovative consumer products. We are looking for a Senior AI Engineer to own and scale the AI layer of one of our core D2C subscription products. You will be fully responsible for production LLM features and the browser automation built around them end to end — prompt systems, structured outputs, evaluation, observability, and model selection — from first experiment to live release, with quality, reliability, and cost as your accountability.
This is a high-impact role suited for someone who decides with data, not intuition. You work in a modern TypeScript stack — Next.js, Cloudflare Workers and Containers with Hono, Hatchet task queues, Drizzle on Supabase Postgres, Vercel Blob. Prompt Systems & Structured Outputs
Design dynamic prompt templates with conditional logic and context injection that maximise generation quality
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
Ship automations as frozen, published workers — versioned, reproducible, and safe to roll back
Build evaluation pipelines — test datasets, LLM-as-a-judge, RAGAS-style metrics — and score responses and screen classifications in Langfuse
Run A/B experiments across models and prompts through an AI gateway (OpenRouter, Cloudflare AI Gateway); Take AI features from experiment to live production on Cloudflare Workers and Containers, and stay accountable after release
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 experience with dynamic prompting — content that depends on input variables and injected context
Structured outputs in production: Experience with unified LLM APIs or AI gateways (OpenRouter, Cloudflare AI Gateway): rate limits, fallbacks, cost-effective model selection
Decides on benchmarks and trace data, not intuition
Ruby Labs operates within the CET (Central European Time) zone. Remote Work Environment:
Paid National Holidays:
Celebrate and relax on national holidays with paid time off to unwind and recharge.
Flexible Independent Contractor Agreement:
Benefit from tax advantages, networking opportunities, reduced employment obligations, and the freedom to work from anywhere. Be part of our fast-growing team and seize this excellent opportunity for personal and professional growth!
After submitting your application, we conduct a thorough review which typically takes 3 to 5 days, but may occasionally take longer due to the volume of applications received. Life at Ruby Labs
At Ruby Labs, we move fast, aim high, and expect the same from our team. If you’re hungry to achieve, motivated by impact, and want to grow at the speed of your own ambition, Ruby Labs offers the platform to make it happen.
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