25+ Years of Engineering Excellence
Don Mario
Engineering Leadership | AI Transformation | Delivery Excellence
An offer you can't refuse: proven Engineering Manager with mastery in building high-performing teams, cutting-edge AI expertise, and a track record of transforming engineering organizations. Available for Engineering Manager, IT Director, or CTO roles.
Don Mario's Trusted Advisor
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Ask about Don Mario's expertise in engineering leadership, AI transformation, team building, or how he can help your organization.
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What Don Mario Brings to the Table
The Family's Expertise
Engineering Leadership
Over seven years leading teams of more than sixty engineers. Reduced incidents to near zero, cut project costs by fifty percent, delivery overruns by ninety-one percent. Built stable, high-performing teams with low turnover through clear ownership and mentoring.
AI & Agentic Systems
Hands-on expertise with TensorFlow, neural networks, and production-ready AI systems. Leading Applied AI transformation with practical, business-focused use cases. Fluent in Python, data analysis, and automation.
Delivery Transformation
Recovered one and a half year delays, reduced critical incidents from one hundred sixty-eight per month to four per year, cut resolution time from sixteen hours to thirty-two minutes. DevOps mastery, architecture excellence, and risk management.
Team Development
Trained many SQL specialists, JavaScript developers, Vibe Coders, and AI specialists. Created mentoring programs that build capability and reduce dependencies. Strong in facilitation, change management, and competency development.
Engineering Leader & AI Visionary
About Don Mario
"In business, as in life, you need someone who delivers results—not excuses."
Mariusz Walczak (Don Mario) brings over twenty-five years of technical excellence combined with more than seven years of proven engineering leadership. Specializes in transforming underperforming teams into high-output organizations while maintaining quality and reducing risk. The approach combines hands-on technical depth with strategic thinking, bridging engineering and business priorities seamlessly.
Bachelor of Science in Software & Database Engineering | Change Management Practitioner | Management 3.0 | Six Sigma Black Belt | TensorFlow & Neural Networks Certified
Leadership Track Record
Engineering Manager at RTV EURO AGD leading more than sixty engineers. Previously led transformations at MODIVO, createIT, and SoftFin. Proven ability to stabilize teams and scale delivery.
Measurable Impact
Cut project costs by fifty percent, reduced delivery overruns by ninety-one percent, incidents from one hundred sixty-eight per month to four per year. Enabled seventeen market launches in two weeks. Recovered one and a half year delays through disciplined execution.
Technical Mastery
Full-stack: JavaScript, TypeScript, PHP, Python, SQL. Cloud: AWS, GCP, Azure. AI: TensorFlow, neural networks. DevOps, Kafka, distributed systems. Architecture and tooling expertise.
Agentic AI & Modern Stack
At the leading edge in Applied AI and Agentic systems. Practical experience building production-ready AI solutions. Comfortable working with AI agents and automation at scale.
Team Builder & Mentor
Trained many developers including Vibe Coders and AI specialists. Creates mentoring programs that strengthen teams and build long-term capability. Focuses on ownership, autonomy, and sustainable growth.
International Experience
English (C1), German (A2), Polish (native). Based in Warsaw. Available for Engineering Manager, IT Director, or CTO roles, or for consulting engagements.
Live Demos
The Portfolio
Each project runs independently on its own subdomain. Click through — they're live, they use real AI, and they show cost per operation in real time.
RoboLam — Product Search
3-Tier RAG · Meilisearch · BGE-m3 · Claude
Intelligent product catalog search for 50 000+ items. Auto-selects the cheapest search strategy per query — fulltext BM25 for simple lookups, semantic embeddings for intent, Claude LLM only when needed. Shows latency, tier used, and cost per search.
Connie — Sales Chat
RAG · Claude Haiku 4.5 · Product knowledge base
AI sales advisor grounded in a real product catalog and company documents. Answers questions about products, delivery, returns — with source citations and confidence scores. Tracks token usage and cost per message live.
RL Pricing Simulator
Q-Learning · APO · Fixed baseline · Flask
Educational demo comparing three pricing strategies for limited inventory — fixed price, analytical optimizer, and a Q-Learning agent that learns purely from trial and error. Interactive parameters, playback mode, training curve visualization.
HR Helper — Attrition Analytics
XGBoost · Synthetic data · What-if scenarios
Predict employee churn risk (30/60/90-day horizon) and delivery throughput for engineering teams. Simulates what-if policies — e.g. "what happens if we speed up ticket review?". Built on 200 synthetic employees, 5 departments, 5 ML models.
See How I Work
Don Mario's Portfolio
Watch real-world examples of engineering leadership in action, AI implementations, team transformations, and delivery excellence. This is how Don Mario operates—with precision, strategy, and results.
Demonstrations of leadership techniques, AI implementations, architecture decisions, and problem-solving approaches. The proof is in the execution.
Watch on YouTubeLet's Discuss Your Needs
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Looking for an Engineering Manager, IT Director, or CTO? Need consulting on AI transformation or delivery excellence? Let's talk.
Direct Contact
Leave a Message
"If you wish to leave a message for Don Mario, the form beside you is the proper channel. Every word will reach his desk — undisturbed."
Call Me
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+48 662 739 382
📍 Warsaw, Poland