Maciej Slawinski, Developer in Gibraltar, Gibraltar
Maciej is available for hire
Hire Maciej

Maciej Slawinski

Verified Expert  in Engineering

Java Developer

Gibraltar, Gibraltar
Toptal Member Since
January 29, 2020

Along with being a BDD advocate, Maciej is an expert Java developer with over eight years of professional experience with broad and detailed knowledge of the Spring framework. He specializes in the back end—architecting, implementing, and deploying highly available microservice-oriented applications.


GitLab, Apache Kafka, MongoDB, Hazelcast, Spring Integration, Spring Cloud...
Grand Parade
RESTful Development, Architecture, Cassandra, Spring Data, Spring Boot, Spring...
Ocado Technology
Git, Apache Maven, Oracle Database, Selenium, Hibernate, Apache Struts...




Preferred Environment

Linux, IntelliJ IDEA, Spring, Java

The most amazing...

...thing I've done was to reduce the response times by 10x in one application by redesigning and reimplementing the caching mechanisms.

Work Experience

Java Developer

2018 - PRESENT
  • Developed a microservice that combines all access restrictions for accounts to play casino games.
  • Migrated over 20 microservices from on-premise VMS to Kubernetes.
  • Prepared continuous integration scripts to deploy all microservices from a GitLab pipeline.
  • Prepared the environment for smoke tests to enable automatic deployments.
  • Migrated over 20 microservices to Java 11 and Spring Boot 2.
  • Helped with induction to new joiners in the team by mentoring and showing the functionality of microservices.
Technologies: GitLab, Apache Kafka, MongoDB, Hazelcast, Spring Integration, Spring Cloud, Spring Boot, Spring, Java

Java Developer

2017 - 2018
Grand Parade
  • Providing an online gaming and betting platform for Grand Parade, a part of William Hill company.
  • Migrated two services from Spring MVC to Spring Boot.
  • Created automation scripts and used Jenkins CI to improve the deployment process.
  • Introducing caching mechanisms that improved the performance of the services.
  • Worked as an active member of the recruitment team and introduced relevant improvements.
  • Introduced TDD culture and enforced writing tests for all functionalities.
Technologies: RESTful Development, Architecture, Cassandra, Spring Data, Spring Boot, Spring, Java

Java Developer

2013 - 2017
Ocado Technology
  • Worked for Ocado, an eCommerce company that sells and delivers food from automated warehouses.
  • Integrated PayPal payments and login with PayPal functionality.
  • Refactored a monolithic application to a microservices architecture.
  • Implemented a framework for end-to-end test automation.
  • Worked closely with the business to deploy new functionalities.
  • Integrated an online web store with Apple Pay payments.
  • Acted as a team leader for a few months, working closely with the product owner on prioritizing and estimating tasks.
Technologies: Git, Apache Maven, Oracle Database, Selenium, Hibernate, Apache Struts, Spring Boot, Spring, Java

Software Engineer

2011 - 2013
  • Built an automated suite for IBM ITM monitoring tool testing.
  • Implemented automated installation of IBM ITM products.
  • Integrated the IBM RFT test framework and IBM RTC test management tool.
  • Reduced the time required for yearly product releases by increasing automated test coverage.
Technologies: IBM WebSphere, IBM Rational Team Concert (RTC), RFT, Eclipse Plugin Development Environment (PDE), Java

Pay With PayPal at

I introduced a new payment method at the eCommerce website, I worked as a back-end developer responsible for analyzing and implementing integration with PayPal payments API and automating end-to-end tests.

Mobile SMS Microservice at Grand Parade

The project was about creating a generic microservice that all of the company's applications could use; the apps had been using various SMS providers. The service needed to unify the contracts between apps and providers along with the ability to choose which provider the app uses.

I worked as a back-end developer and was responsible for architecting and implementing the complete solution.

Casino Restrictions Service at BetVictor

The project's aim was to create a service that holds all of the legal and company restrictions for allowing customers to play online casino games.

I worked as a back-end developer—responsible for gathering the requirements, architecting the solution, and implementing and writing integration tests.

Migration to Google Cloud at BetVictor

I was responsible for migrating over 25 microservices from an on-premise VMOS deployment solution to Google Cloud on Kubernetes. As part of the project, I created automated deployment and test pipelines in GitLab as well as creating shared deployment scripts.
2009 - 2014

Master's Degree in Computer Science

AGH University of Science and Technology - Krakow, Poland


Web Application Security





IntelliJ IDEA, GitLab, Apache Maven, Git, IBM Rational Team Concert (RTC)


Spring Boot, JUnit, Spring Integration, Spring Security, Spring, Apache Struts, Hibernate, Selenium


Java, Java 11, SQL


REST, Microservices, RESTful Development


Hazelcast, Cassandra, Spring Data, MongoDB


Linux, Oracle Database, IBM WebSphere, Apache Kafka


Spring Cloud, Architecture, Eclipse Plugin Development Environment (PDE), RFT

Collaboration That Works

How to Work with Toptal

Toptal matches you directly with global industry experts from our network in hours—not weeks or months.


Share your needs

Discuss your requirements and refine your scope in a call with a Toptal domain expert.

Choose your talent

Get a short list of expertly matched talent within 24 hours to review, interview, and choose from.

Start your risk-free talent trial

Work with your chosen talent on a trial basis for up to two weeks. Pay only if you decide to hire them.

Top talent is in high demand.

Start hiring