Hello, I'm
Kristian Lonergan
Senior Frontend Developer
Building exceptional user experiences with modern web technologies. Passionate about clean code, mentorship, and delivering reliable products.
About Me
I'm a Senior Frontend Developer with over 10 years of experience building modern web applications. I specialise in creating responsive, performant, and accessible user interfaces with a strong focus on code quality and team collaboration.
At Propylon, I serve as a line manager and code owner of two key applications, overseeing both internal developers and external contractors. I enjoy combining technical depth with leadership to help teams deliver great products.
Core expertise
Technical Skills
Technologies, tools, and practices I work with daily to deliver high-quality software.
Frontend
State Management
Testing
Tools & Workflow
Leadership & Delivery
Work Experience
Over a decade of building, leading, and delivering modern web applications.
Propylon
January 2024 - Present
Senior Frontend Developer
January 2024 - Present- Code owner of the Request System (web) and its mobile application, overseeing architecture and feature delivery
- Acting line manager with responsibility for team members and oversight of external contractors
- Lead bi-weekly code reviews and provide technical mentorship across the frontend team
- Migrated the E2E test suite from Cypress to Playwright, improving reliability and speed
- Develop Microsoft Word add-ins with Office.js and React; drive frontend best practices and documentation
Rezexe
March 2020 - December 2023
Senior Frontend Developer
January 2022 - December 2023- Led frontend development for a high-traffic marketplace platform using React, TypeScript, and Material UI
- Architected a Next.js monitoring dashboard for AWS container health with real-time updates
- Established CI/CD pipelines, code review practices, and frontend documentation standards
- Designed and implemented E2E testing strategy using Cypress
Frontend Developer
March 2020 - December 2021- Built key features for a marketplace platform with React, TypeScript, and Material UI
- Created a reusable component library and integrated REST APIs with Redux and React Query
- Delivered comprehensive unit tests with Jest and React Testing Library
Career Break
September 2019 - February 2020
European Travel & Professional Development
September 2019 - February 2020- Travelled across Europe, attended tech meetups, and completed online courses in modern web technologies
IBM
June 2014 - August 2019
Software Engineer
April 2017 - August 2019- Developed enterprise web applications and led migration from legacy Dojo to modern JavaScript frameworks
- Built Java backend services and RESTful APIs; mentored junior developers across global teams
- Created proof-of-concept applications using React and modern tooling
Software Test Engineer
June 2015 - March 2017- Designed automated test frameworks with Java and Selenium, significantly reducing manual testing effort
- Maintained CI test suites and conducted performance testing to identify bottlenecks
Software Test Engineer Intern
June 2014 - May 2015- Developed and maintained automated test suites using Java and Selenium within an Agile team
Get In Touch
Interested in working together or have a question? I'd love to hear from you.
Let's connect
I'm always interested in hearing about new projects, opportunities, and collaborations. Feel free to reach out through any of the channels below.