AI Engineer

About the Role: At RubyLabs, we're seeking a senior AI Engineer (Node.js / Next.js / TypeScript) to shape our AI infrastructure and drive production-ready LLM experiences. You'll own advanced prompt systems, structured outputs, and complex LLM workflows using LangChain or LlamaIndex, taking full ownership of key AI features from experimentation to live production.

What You'll Do

• Design complex, dynamic prompt templates with conditional logic to maximize generation quality and reasoning.
• Implement various response schemes (JSON mode, function calling) to ensure AI outputs are predictable.
• Build robust evaluation pipelines and use Langfuse to score the quality of responses in real-time.
• Perform deep debugging of complex LLM chains to identify bottlenecks and optimize for cost and latency.
• Run systematic A/B experiments across different models via OpenRouter (e.g., Claude 3.5 Sonnet vs. GPT-4o).

What You Bring

• Deep knowledge of Node.js & Next.js to build reliable services and handle complex LLM-generated data.
• Proven experience in building dynamic prompts and context injection.
• Experience working with unified APIs like OpenRouter, managing rate limits, and model selection.
• Understanding of LLM observability principles (Langfuse or similar) and evaluation methodology (RAGAS).
• Bonus: Practical experience in fine-tuning models, RAG Architecture, and basic Python knowledge.

Benefits

• Remote Work Environment with the freedom to work from anywhere within ± 4 hours of CET.
• Unlimited PTO and Paid National Holidays.
• Company-provided Apple MacBook.
• Flexible Independent Contractor Agreement offering autonomy, tax advantages, and networking opportunities.