MarceliGrabowski
Senior Developer & Technical Lead Remote / Wrocław ● Available for Consulting
Resilient Technical Lead with an architecture-first mindset. Specializing in legacy rescue, cost optimization, and scalable cloud solutions.
8+
Years Exp
100+
Interviews
What I Do
01
Legacy System Rescue
Reverse-engineer, stabilize, and modernize undocumented or abandoned codebases.
02
Cloud Architecture
Design scalable infrastructure on AWS, GCP, Azure, or self-hosted VPS.
03
Technical Leadership
Lead teams, establish standards, and mentor developers to ship faster.
04
Cost Optimization
Audit cloud spending and implement strategies to cut costs without sacrificing performance.
Experience
2025 Sep 2025 - Present
Holisticon Insight
IoT Legacy Rescue & NextGen Platform
- Legacy Rescue Reverse-engineered an undocumented Java/Liferay ecosystem for a US beverage manufacturer to stabilize operations.
- Impact Resolved critical security issues (vendor secrets, Entra ID) and containerized legacy apps.
- Modernization Leading the design of a NextGen .NET 10 platform on Azure (ADX, Functions).
- Tech .NET 10, React 19, TanStack Router, Bicep, Java 8, Liferay.
2023 May 2023 - Sep 2025
Holisticon Insight
IoT Energy Services Platform
- Role Technical Leader for a team of 5, building an energy efficiency platform for a major US appliance manufacturer.
- Crisis Management Engineered and deployed critical infrastructure in 4 days to bridge a sudden staffing gap.
- Cost Optimization Engineered a migration strategy for high-throughput AWS Lambda service, reducing monthly costs by 60%.
- Architecture Designed multi-region serverless architecture (AWS/GCP) maintaining 99.9% uptime. Introduced Kotlin, GraalVM, and Gradle standards.
- Tech Java 21, Spring Boot 3, Kotlin, AWS Lambda, GCP Cloud Run.
2021 Oct 2021 - May 2023
Xebia (formerly PGS Software)
Senior Software Developer
- Integration Unified data from 4 external fleet telemetry providers for a UK connected vehicle data company.
- DevOps Engineered Kubernetes/ArgoCD GitOps workflows and implemented Tilt for local development.
- Mentorship Upskilled a 5-person team on Azure services.
- Tech Java 17, Scala 2, Kafka, Kubernetes, Azure AKS, Terraform.
2018 Sep 2018 - Sep 2021
Objectivity
Software Developer
- Architected a new taxonomy service for a leading European Online Car Market (Java 11, Spring WebFlux, AWS).
- Proposed and implemented Quarkus for a new high-performance E-commerce Search Engine.
- Accelerated delivery for a major banking group (Leasing Platform) using Java & Azure.
Technical Index
Backend
- Java (8-21)
- Kotlin
- Scala
- C#
- Deno
- Spring Boot
- Quarkus
- Dropwizard
- .NET (ASP.NET Core)
Frontend
- Angular
- React 19
- Astro
- RxJS
- Tanstack Router/Query
- TailwindCSS
- TypeScript
Cloud & Infra
- AWS
- GCP
- Azure (ADX, ADF)
- VPS / Self-hosted
- Docker
- Kubernetes
- Terraform
- Bicep
- GitHub Actions
- ArgoCD
Observability
- Prometheus
- Grafana
- OpenTelemetry
- Azure Monitor
- Elasticsearch
Contact
Have a project in mind? Let's discuss how I can help.