Ruby Labs

About the role

Ruby Labs is hiring an experienced Senior Data Analyst to join our fast-paced and rapidly growing team for our new product - job application platform, that streamlines the job search process for professionals.

In this role, you'll collect, categorize, and analyze data to create actionable reports that drive decision-making across the company. You'll uncover insights, identify growth opportunities, establish key benchmarks, and ensure we deliver a product that truly satisfies our customers' needs.

We expect you to take full ownership of data pipelines, analytics, and insights – ensuring every decision is backed by reliable data. You'll work in a professional and dynamic environment where accuracy matters, constantly validating that our data is meaningful and actionable.

Why Join Us

• Work on an outstanding product: Our platform is trendy, fast-scaling, and redefining how people change their professional roles.
• Make a direct impact: As a Senior Data Analyst, your insights will guide product decisions, influence the roadmap, and shape user experiences.
• Tackle meaningful challenges: From decoding user intent across millions of interactions to optimising conversion funnels, you’ll face complex and exciting problems every day.
• Grow with us: This is an ambitious journey with huge potential – perfect for someone eager to grow alongside a cutting-edge product and market.

Key Responsibilities

• Partner with Product Owners and Data Teams.
• Create new dashboards, maintain and improve existing reports such as Product Reports.
• User behaviour analysis, aha moment analysis
• Analyse data to generate actionable insights, find trends, patterns and provide recommendations to maximise KPIs.
• Monitor metrics.
• Designing and building robust data models in SQL.
• Give and receive actionable feedback to and from peers and the Leadership Team.

Qualifications

• Degree in an analytical field such as Math, Data Science or Economics.
• At least 3+ years of work experience as a Data Analyst.
• Strong analytical and problem-solving skills, with the ability to identify trends, patterns, and insights in large datasets.
• Excellent verbal communication.
• Ability to think strategically and make data-driven decisions that align with the organisation’s goals.
• Experience in Product Analytics.
• Experience with Mixpanel, GA4, Amplitude or similar.
• Advanced SQL.
• Experience with popular BI tools such as Tableau, Looker, or similar.
• Experience in subscription business.
• Ability to adapt quickly, learn new tools and methods efficiently, and work effectively in a high-pressure, fast-changing environment.

Nice to have

• Strong spoken and written English.
• Experience in Marketing Analytics.
• Experience with Python, R.
• Experience with GCP, BigQuery.
• Experience with Google Ads, Facebook Ads etc.
• Experience with orchestration frameworks such as Airflow.
• Experience with git and code review process.

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. Read more about it here: https://docs.google.com/document/d/1nkrN76JlZkbKj9WSOhlT1_mni_CZeDkHdwfIjPXVwvk/preview?tab=t.0

Be part of our fast-growing team and seize this excellent opportunity for personal and professional growth!

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)
• Interview with Head of Product (60 minutes)
• Final Interview (60 minutes)

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 RubyLabs, we’re seeking a senior AI Engineer (Node.js / Next.js / TypeScript) to shape our AI infrastructure and drive production-ready LLM experiences. You’ll work in a modern stack, making data-driven decisions around model performance, reliability, and cost.

You’ll own advanced prompt systems, structured outputs, and complex LLM workflows using LangChain or LlamaIndex. Observability, debugging, and evaluation are core to the role, leveraging Langfuse and AI gateways like OpenRouter to continuously improve model quality and operational efficiency. You’ll take full ownership of key AI features from experimentation to live production.

Key Responsibilities

• Advanced Prompt Engineering: Designing complex, dynamic prompt templates with conditional logic and efficiently reusing information and context within prompts to maximize generation quality and reasoning.
• Structured Outputs & Schemas: Implementing various response schemes (JSON mode, function calling, Zod/JSON schemas) to ensure AI outputs are predictable and ready for seamless integration into application logic.
• Prompt Engineering & Evaluations: Building robust evaluation pipelines and using Langfuse to collect feedback and score the quality of responses in real time.
• Tracing & Debugging: Performing deep debugging of complex LLM chains using Langfuse traces to identify bottlenecks and optimize for cost, latency, and context window usage.
• AI A/B Testing: Running systematic experiments across different models via OpenRouter (e.g., comparing Claude 3.5 Sonnet vs. GPT-4o) and analyzing results based on quantitative metrics.
• Data-Driven Decisions: Making deployment decisions for new prompts or models strictly based on quantitative benchmarks and trace data, rather than intuition.
• Output Scoring & Analysis: Developing scoring systems to analyze the “Problem → Solution” chain and identify root causes of hallucinations or logic errors using Langfuse analytics.
• Model Performance & Fine-Tuning: Regularly re-evaluating model performance as new architectures emerge and performing fine-tuning when necessary to meet specific domain requirements.

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.

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. 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!

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.