Junior AI Engineer

ABOUT US

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. Learn more about our story at: https://rubylabs.com/about-us/

ABOUT THE ROLE

At Ruby Labs, we are building a Direct-to-Consumer product in the AI category. We’re looking for a Junior AI Engineer (Node.js / Next.js / TypeScript) to join our AI engineering team and contribute to production-ready LLM experiences.

You’ll work alongside senior engineers in a modern stack, learning to make data-driven decisions around model performance, reliability, and cost. You’ll contribute to prompt systems, structured outputs, and LLM workflows while building familiarity with observability and evaluation tooling like Langfuse and AI gateways like OpenRouter.

This is a hands-on role where you will grow quickly by shipping real AI features to production under the guidance of experienced teammates.

KEY RESPONSIBILITIES

- Implement AI-powered product features and workflows based on specifications from senior engineers.

- Write, iterate on, and manage production prompt templates, following established patterns for dynamic prompting and context injection.

- Integrate structured output schemas (JSON mode, function calling, Zod/JSON schemas) to ensure AI responses are predictable and application-ready.

- Build and maintain output enforcement mechanisms such as validators and repair loops under senior guidance.

- Participate in prompt experimentation workflows — drafting variants, running A/B tests across models via OpenRouter, and documenting results.

- Contribute to evaluation pipelines and help score prompt/model quality using Langfuse.

- Write clean, maintainable TypeScript code within the Next.js / Node.js stack.

- Participate in cod...