Senior Fullstack Developer · Warsaw, CET

DawidLeśniewski

// building scalable, cloud-native systems

7+ years of hands-on experience designing, developing and deploying Java-based applications. I specialize in microservices architecture and cloud platforms - turning complex requirements into robust, maintainable systems.

What I do

Services & expertise

01

Backend & Microservices

Designing and developing distributed services with Spring Boot - from architecture and API design to performance and maintainability.

02

Cloud & DevOps

Deploying and scaling applications on Azure with Kubernetes and Docker, including CI/CD pipelines and container orchestration.

03

Legacy Modernization

Refactoring and decomposing monoliths into microservices, upgrading stacks to newer technologies and improving overall efficiency.

04

API & Event-Driven Design

Clean REST API design and event-driven integration with Kafka and RabbitMQ for reliable, decoupled communication between services.

05

Full-Stack Delivery

Backend paired with Angular frontends to ship cohesive, end-to-end features - not just endpoints, but working user experiences.

06

Technical Direction

Helping define technical vision and roadmaps, ensuring engineering decisions stay aligned with business objectives.

How I work

From idea to production

01

Understand

I dig into the problem, constraints and existing code before writing a line - so the solution fits the business, not just the ticket.

02

Architect

Pragmatic design over over-engineering. Clear boundaries, sensible patterns, and a plan that scales without gold-plating.

03

Build & test

Clean, well-tested code shipped in small increments - with CI, reviews and automated checks keeping quality high.

04

Ship & iterate

Deploy to the cloud, monitor what matters, and improve based on real feedback. Done means running in production.

Background

Where I've worked

7+ years building and scaling Java backends across regulated, data-heavy domains - from cloud SaaS platforms to financial-data systems.

Life Sciences /
Biotech SaaS

Designed and scaled Java microservices on Azure for a cloud-based platform, helped shape its technical direction and roadmap, and led the migration from Docker Swarm to Kubernetes alongside upgrades to newer technologies.

Spring Boot 4+Java 21+AngularAzureKubernetesKafkaRabbitMQSQL / NoSQL
Fintech /
Financial Data

Delivered backend and frontend across the full software lifecycle - from requirements and architecture to implementation - and took part in decomposing a monolithic application into microservices.

Spring Boot 3SpringJavaAngularRabbitMQSQL
Toolbox

Technical stack

Backend

JavaSpring BootSpring Data JPAREST APIsMessaging (Kafka, RabbitMQ)Testing (JUnit, Mockito, Testcontainers)SQL / NoSQL

Frontend

AngularTypeScriptJavaScriptHTML / CSS

DevOps & Infra

AzureAWSKubernetesDockerJenkinsMavenGradle
Let's talk

Have a project
in mind?

Drop me a line - I usually reply within a day.