Barry O’Sullivan

86 Meadowgate, Gorey, Co. Wexford

Software Engineer - Architect - DDD Specialist - Conference Speaker - PHP Dublin Organiser

About me

Software developer experienced in high traffic web applications. Architected and implemented multiple products for both startups and established companies. Extensive experience working in existing/legacy codebases and improving quality. Passionate about building software effectively. For the last three years my focus has been legacy PHP, improving my ability to refactor and bring quality to existing systems, now I'm ready to take those skills and apply them in bigger ways.



  • PHP (15yr)
  • MySQL (15yr)
  • HTML/CSS (15yr)
  • Javascript (12yr)


  • CI/CD
  • Agile development
  • Kanban
  • Scrum
  • Event Storming


  • Legacy refactoring
  • Service extraction
  • Event Sourcing
  • TDD
  • DDD


  • Laravel
  • CodeIgniter
  • Zend
  • Slim
  • Express

Core skills

  • Problem solver
  • Fast learner
  • Goal orientated
  • Documentation
  • Metric driven


Adverts.ie (https://adverts.ie):

  • SCA compliance: Replaced entire payment system iteratively with zero downtime
  • Cross-sell: Designed & implemented cross share to DoneDeal feature. Async message based, robust & highly profitable
  • Upsells: Introduced “Orders” iteratively to web & mobile apps so multiple products/upsells could be purchased at once

Journal.ie (https://thejournal.ie):

  • View tracking: Rewrote and fixed high traffic view tracking micro-service with zero downtime
  • Responsive migration: Planned and implemented iterative migration of legacy (12yr+) codebase to responsive layouts
  • Design training: Trained dev team in clean architecture, testing and legacy refactoring


PHP Consultant, Architect & Contractor (2018 - now)

Independent contractor. Worked for theJournal.ie, Adverts.ie and Daft.ie. Specialised in legacy web apps, reverse mapping product behaviour and adding new functionality in an iterative, testable and stable manner. Worked with dev managers to upskill their team in design, refactoring and architecture skills.

Dynamic Reservations: Lead Developer/Architect (2016 - 2018)

Architected and implemented an event sourced product in the travel agency space. Upskilled the team in event sourcing and domain exploration, ensuring we had the skills to execute and build a scalable SPA.

Olive Media: Software Development Manager (2014 - 2016)

Managed the development of a new recruiting application for HiUp. Implemented an event-sourced, domain aligned product, with a microservice based architecture. Looked after all aspects of development, including Android and FE Javascript.


Trinity College Dublin (2008 - 2009)
Msc Computer Science
Trinity College Dublin (2004 - 2008)
BA(mod) Computer Science

References are available on request