Dionysios Efstathiou

Software Engineer

Passionate about developing, deploying and maintaining software products. I always aim at using the right tools for automating processes and improving development experience. I am a fan of the motto "if you need to do it at least twice, automate it".

Phone: 07706500927
Address: 44 - 50 Abbey Road, IG11 7SA, Barking, London
Website: http://dionysios.co.uk/


Index Labs

Senior Software Engineer

September 2020 - present

Member of a software engineering team for providing and supporting software features and technical infrastructure for the online stock market Football Index. Utilising mob programming daily which enables every member of the team to have hands-on experience with every aspect of back-end, front-end and mobile development and unit, integration, automated end-to-end and manual QA testing of features. I use daily NodeJS, Kotlin, Java, Spring, Micronaut, Mockito, WireMock, Docker, Gitlab, JIRA, Confluence, Logz.io and AWS cloud services such as SQS, Redis, S3 and others.


Software Engineer

August 2019 - September 2020

I was a member of a team responsible for designing, developing and maintaining back-end microservices for optimising the revenues for Expedia Partner Solutions. I used daily Java, Spring, Micronaut, Spock, Mockito, WireMock, JIRA, Confluence, Splunk and AWS cloud services such as EC2, ECS, Cloud Formation, S3, Load Balancers, Serverless Functions (Python/NodeJS) and others. I worked using Scrum and took part in all the ceremonies. In terms of CI/CD tooling I use among others Jenkins, Bamboo, Git, GitHub, Gradle, SonarQube and Docker. 

Biggest achievements:

  • I drove my team's AWS infrastructure costs down at a rate of 70-80% by identifying, proposing and implementing optimisations and migrations for improving the cost-efficiency of our services. 
  • I also communicated good practices, motivated and took part into implementing those in teams within and outside my tribe's boundaries. 

Capital One

Software Development Engineer

March 2019 - August 2019

Worked in a scrum team of 8 engineers responsible for the development of RESTful back-end micro-services deployed on Amazon Web Services for supporting complex customer service systems. I was responsible for improving the quality of the software services under development and testing and for promoting the automation of their testing, deployment and release process. I worked daily with Java, Spring, JUnit, Mockito, Cucumber, WireMock, Jenkins, IntelliJ, macOS, Amazon Web Services such as EC2, S3 and Lambda.


Senior Software Engineer

September 2014 - February 2018

In my last role I was member of a team responsible for continuous integration and improving development processes within Alfa. I was responsible for upgrading our integration test framework for automated functional testing and providing support for detecting and reacting to performance regressions. I provided various optimisations improved which reduced the total run time of the 2,500 integration tests suite by 20%. I also took part in an internal migration project to automatically convert more than 250 Java modules built by Ant (and Ivy for dependency management) to be able to built and managed by Maven. I worked with Java, Guice, JUnit, Mockito, Selenium, Bamboo, Oracle, MySQL, Linux/Unix, Jetty, JBoss EAP, Tomcat, JMS, JMX, REST, SOAP and use day-to-day Eclipse, SVN, Jira, FishEye, JProfiler, Docker, Maven, Ant and Ivy.

In another role, I was the technical lead on a migration project which involved the development, bug fixing, performance improvements and carrying out releases of the migration application for transforming the legacy system data to Alfa Systems.

King's College London

Marie Curie Fellow

September 2011 - August 2014

Participated in a European research project with leading  Software Engineering universities across multiple countries and got exposed to the latest technologies, platforms and tools in the area of engineering and provisioning of service-based cloud applications. 

I used Java, Linux Scripting, R, Amazon EC2, Latex and Eclipse while I had the chance to prepare research publications, perform presentations and present research results in international conferences and workshops.

Computer Technology Institute

Research and Development Engineer

June 2010 - August 2011

Algorithmic and test-bed implementation on Internet on Things networks. I published 10 research papers in peer-reviewed international conferences and workshops.


King's College London

Doctor of Philosophy (PhD), Informatics

2011 - 2014

Machine learning techniques and optimisation algorithms implemented in a Java-based research prototype which interacted with R statistical environment and used Amazon EC2 to perform scalable experiments.

Computer Engineering & Informatics

MSc, University of Patras

2009 - 2011

Degree: 9.52/10 (Top 5% of my class).

Computer Engineering & Informatics

Diploma, University of Patras

2004 - 2009

Degree: 8.24/10 (Top 10% of my class).