Senior AI Engineer

About the role

Ruby Labs is seeking a Senior AI Engineer to own and drive the quality, reliability, and evolution of its production AI systems. In this high‑ownership role you will deliver major AI features, ensure production stability, and run data‑driven experiments using tools such as Langfuse, Mixpanel and OpenRouter.

Key responsibilities

• Design, implement and maintain output‑type based AI systems, including segmentation, routing and enforcement.
• Integrate multiple LLM providers via OpenRouter, manage model selection, fallback strategies and cost optimisation.
• Build and orchestrate agentic, tool‑using AI workflows with clean tool contracts and function‑calling interfaces.
• Develop production prompt systems, run A/B tests across models and analyse impact.
• Monitor AI system metrics, latency and health using Langfuse and other observability tools.

Required profile

• 6+ years of backend/full‑stack engineering experience with production‑grade TypeScript/Node.js.
• 2+ years building AI/LLM systems in production (exceptional candidates with less experience considered).
• Hands‑on experience with LLM APIs (OpenAI, Anthropic or similar) and agentic AI workflows.
• Strong ownership mindset and responsibility for engineering quality.

Required skills

• TypeScript, Node.js, Next.js
• Redis, PostgreSQL
• LLM APIs (OpenAI, Anthropic), OpenRouter
• Langfuse, LangChain, LlamaIndex
• Agentic AI, tool contracts (MCP), RAG pipelines
• Python for data‑science scripts (optional)

What we offer

• Fully remote work environment
• Unlimited paid time off and paid national holidays
• Company‑provided MacBook
• Flexible independent contractor agreement with tax advantages