ruby-labs - AI Engineer (Junior-level)
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Requirements
• 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. • Experience with AI-centred development tools (Cursor, Claude Code, Windsurf, or similar). • Experience with LLM observability tools (Langfuse, LangSmith, or similar). • Exposure to AI gateways such as OpenRouter or model routing concepts. • Exposure to AI agents, tool use/function calling, or the Model Context Protocol (MCP). • Familiarity with evaluation frameworks (RAGAS, custom LLM-as-a-judge systems). • Familiarity with LLM orchestration frameworks (LangChain, LlamaIndex) or RAG concepts. • Familiarity with Python (e.g., for evaluation or data scripts). • Experience with Redis or real-time data systems. • Experience working in startup or fast-paced product environments. • Ruby Labs operates within the CET (Central European Time) zone. Applicants from any country are welcome to apply for the position as long as they are located within approximately ± 4 hours of CET. This ensures optimal collaboration and communication during working hours.
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. • 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.
Benefits
• Discover the perks of being part of our vibrant team! We offer: • 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. Read more about it here: https://docs.google.com/document/d/1nkrN76JlZkbKj9WSOhlT1_mni_CZeDkHdwfIjPXVwvk/preview?tab=t.0#heading=h.ndsdl4wapxtt • Be part of our fast-growing team and seize this excellent opportunity for personal and professional growth!
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