Qualifications

• Node.js & Next.js: Deep knowledge of the stack to build reliable services and handle complex LLM-generated data.
• Dynamic Prompting Skills: Proven experience in building prompts where content is highly dependent on input variables and context injection.
• OpenRouter Experience: Experience working with unified APIs, managing rate limits, and selecting the most cost-effective models for specific tasks.
• Langfuse (or similar): Understanding of LLM observability principles — setting up tracing, creating test datasets, and integrating scoring systems.
• Evaluation Methodology: Experience with frameworks like RAGAS or building custom “LLM-as-a-judge” systems.
• Analytical Mindset: Ability to transform raw generation logs into actionable business metrics and technical insights.
• Iterative Mindset: Focus on continuous product improvement through constant feedback loops.
• Fluency in Russian and/or Ukrainian.

Nice to have

• Fine-Tuning: Practical experience in fine-tuning models for specific domain tasks or JSON compliance.
• RAG Architecture: Understanding how to build and optimize Retrieval-Augmented Generation systems, including indexing, retrieval, and re-ranking.
• Python: Basic knowledge for working with data science scripts or AI evaluation libraries.

Location

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.

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.

Interview Process

After submitting your application, we conduct a thorough review which typically takes 3 to 5 days, but may occasionally take longer due to the volume of applications received. If we see a potential fit, we proceed with the following steps:

• Recruiter Screening (40 minutes)
• Technical Interview (60 minutes)
• Final Interview (30 minutes)

Life at Ruby Labs

At Ruby Labs, we move fast, aim high, and expect the same from our team. We’re not here to play small—we’re here to build, grow, and win. That means we look for people who are ambitious, driven, and ready to give their best every single day.

This is a place for individuals who thrive under pressure, embrace challenges, and see opportunity in every obstacle. If you’re hungry to achieve, motivated by impact, and want to grow at the speed of your own ambition, Ruby Labs offers the platform to make it happen.

Here, effort is matched with reward. We recognize those who go all in and deliver results, and we create space for people who want more—more responsibility, more growth, and more success.