Junior AI Engineer

Ruby Labs

Junior AI Engineer developing AI features in a remote role for Ruby Labs' innovative consumer products. Collaborating with senior engineers and integrating AI technologies.

Posted 6/9/2026full-timeRemote • 🇪🇺 Anywhere in EuropeJuniorWebsite

Tech Stack

Tools & technologies

JavaScriptNext.jsNode.jsTypeScript

About the role

Key responsibilities & impact

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.
Participate in prompt experimentation workflows by drafting variants, running A/B tests across models via OpenRouter, and documenting results.
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.
Help implement tool calling and function calling integrations so AI features can fetch data or trigger actions, following patterns established by senior engineers.
Contribute to evaluation pipelines and help assess prompt and model quality using Langfuse.
Write clean, maintainable TypeScript code within the Next.js and Node.js stack.
Participate in code reviews and incorporate feedback.
Document technical decisions and system behaviour to support knowledge sharing.
Collaborate with product, growth, data, and billing teams to deliver features on time.

Requirements

What you’ll need

0–2 years of software engineering experience — recent graduates, bootcamp graduates, and early-career engineers are welcome.
Working knowledge of Node.js, Next.js, and TypeScript.
Basic understanding of how LLMs work and hands-on experience using LLM APIs (OpenAI, Anthropic, or similar).
Experience writing prompts that go beyond simple instructions, such as using variables, templates, or conditional logic.
Familiarity with structured outputs (JSON mode, function calling, or schema validation).
Understanding of basic web application architecture, RESTful APIs, and backend fundamentals, including request validation, error handling, and logging.
Curiosity and willingness to learn quickly in a fast-moving AI product environment.
Strong communication skills and a collaborative mindset.

Benefits

Comp & perks

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.

ATS Keywords

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Applicant Tracking System Keywords

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Hard Skills & Tools

TypeScriptNode.jsNext.jsprompt engineeringA/B testingJSONfunction callingschema validationRESTful APIsweb application architecture

Soft Skills

communicationcollaborationcuriositywillingness to learn