Fullstack Senior Data Scientist
Senior Fullstack Data Scientist in Warsaw: lead GenAI architecture and hands-on delivery, mentor teams, ship production ML pipelines for enterprise clients.
We usually respond within a day
Location: Warsaw, Poland (fully remote or office, your choice)
Salary: PLN 105 to 170/hour B2B
Contract: B2B
What this company does
This is a data and analytics services company, founded in 2008, working with over 75 large consumer goods brands across 30 countries. The work covers AI and machine learning, supply chain analytics, customer analytics, data platforms, and digital commerce. Clients are big, the engagements are complex, and the expectations are enterprise-grade.
Why this role exists
The company is building and delivering GenAI solutions for large clients in retail, CPG, and manufacturing. They need someone who can both lead the technical direction of those projects and stay hands-on throughout the full build. This is not a research role and it is not a management-only role. You will make architectural decisions and also write the code.
What you will do
Lead the design and discovery phase for GenAI projects: translate business problems into concrete architectures covering model selection, RAG, agents, fine-tuning, and guardrails
Build complete GenAI solutions end to end, covering data ingestion, retrieval layers, orchestration (LangChain, LlamaIndex, LangGraph), API and backend
Design RAG pipelines using vector databases, hybrid search, rerankers, query transformation, and evaluation frameworks
Own prompting strategies, model selection, and fine-tuning approaches including LoRA, QLoRA, and supervised fine-tuning
Implement safety and governance controls: input/output filters, PII handling, audit logs, human-in-the-loop mechanisms
Gather technical requirements directly from client stakeholders and produce reliable delivery estimates
Mentor other data scientists and engineers on GenAI patterns, code quality, and best practices
Track the GenAI landscape actively and run targeted proof-of-concepts on emerging approaches
What the job actually looks like
You will work directly with international clients, often translating complex technical choices into language that non-technical stakeholders can act on
Engagements are with large enterprises in retail, CPG, and manufacturing. These clients have complex legacy environments, change management processes, and compliance requirements
You will be responsible for both the architecture decisions and the code quality on the same project, with other engineers looking to you for direction
The work involves production systems, not pilots. If something breaks in production for a major retail client, you are part of the response
What this role requires
6 or more years in Data Science or AI engineering with a track record of shipping production systems, not just prototypes
4 or more years writing production-ready Python for AI and ML workloads: clean, maintainable, deployable code
2 or more years of hands-on production experience with LLM-based systems, including RAG pipelines, agent frameworks, and evaluation
The ability to make architectural decisions under uncertainty and defend them clearly to both technical and non-technical audiences
Fluent English for direct client communication
What this role does not include
Research-stage or experimental-only work. Everything here is built to run in production
A small-team environment. You will be working within a structured consulting organisation with its own processes, governance, and delivery standards
Founder-level autonomy. You will have significant technical ownership, but within client contracts and delivery commitments
Compensation and working conditions
PLN 105 to 170 per hour on B2B contract depending on experience
Fully remote or office-based, your choice
Workation policy available for defined periods
Dedicated onboarding buddy from day one
Unlimited Udemy access and 110 or more training opportunities per year
Internal promotion pathways: 76% of promotions are internal
- Department
- Python (AI/ML, data science, web via Django/Flask)
- Locations
- Warsaw
- Remote status
- Hybrid
- Hourly salary
- PLN105 - PLN170
- Employment type
- Full-time
- Employment level
- Professionals
- Recruitment Speed
- 14 days