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I'm Theodoros Itzaris, a Senior Frontend / Software Engineer in the United Kingdom. I specialize in building high-performance digital experiences and leading teams through complex system migrations to modern frameworks such as Next.js, React, and GraphQL, while improving accessibility and performance. I thrive on aligning design, product, and backend collaboration, implementing feature flags, analytics-driven iterations, and nurturing growth through mentoring and one-on-one conversations. I value clean architecture, scalable UX, and a culture of learning and innovation.…I'm Theodoros Itzaris, a Senior Frontend / Software Engineer in the United Kingdom. I specialize in building high-performance digital experiences and leading teams through complex system migrations to modern frameworks such as Next.js, React, and GraphQL, while improving accessibility and performance. I thrive on aligning design, product, and backend collaboration, implementing feature flags, analytics-driven iterations, and nurturing growth through mentoring and one-on-one conversations. I value clean architecture, scalable UX, and a culture of learning and innovation.

Theodoros Itzaris

Front-End Developer, Full Stack Developer, Web Developer, +2

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I'm Theodoros Itzaris, a Senior Frontend / Software Engineer in the United Kingdom. I specialize in building high-performance digital experiences and leading teams through complex system migrations to modern frameworks such as Next.js, React, and GraphQL, while improving accessibility and performance. I thrive on aligning design, product, and backend collaboration, implementing feature flags, analytics-driven iterations, and nurturing growth through mentoring and one-on-one conversations. I value clean architecture, scalable UX, and a culture of learning and innovation.…I'm Theodoros Itzaris, a Senior Frontend / Software Engineer in the United Kingdom. I specialize in building high-performance digital experiences and leading teams through complex system migrations to modern frameworks such as Next.js, React, and GraphQL, while improving accessibility and performance. I thrive on aligning design, product, and backend collaboration, implementing feature flags, analytics-driven iterations, and nurturing growth through mentoring and one-on-one conversations. I value clean architecture, scalable UX, and a culture of learning and innovation.

Available to hire

I’m Theodoros Itzaris, a Senior Frontend / Software Engineer in the United Kingdom. I specialize in building high-performance digital experiences and leading teams through complex system migrations to modern frameworks such as Next.js, React, and GraphQL, while improving accessibility and performance.

I thrive on aligning design, product, and backend collaboration, implementing feature flags, analytics-driven iterations, and nurturing growth through mentoring and one-on-one conversations. I value clean architecture, scalable UX, and a culture of learning and innovation.

Skills

Experience Level

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Intermediate

Intermediate

Intermediate

Language

English

Fluent

Greek, Modern

Fluent

Work Experience

Front End Lead at Maxximus (maxximus.uk)

June 1, 2025 - Present

Led frontend development for the Maxximus web platform, transitioning from a monolithic React app to a Next.js-based monorepo with modular packages to improve maintainability and performance. Focused on accessibility, reliability, and performance optimization, while mentoring engineers through regular one-on-one sessions. Collaborated with design and backend teams to refine user journeys and define API strategies, and managed stakeholder expectations via epics and priority planning. Implemented real-time video calling via Daily.co with GraphQL integration and updated CI/CD pipelines to support new deployment environments.

Senior Frontend Engineer at qa.com - platform.qa.com

April 1, 2023 - May 1, 2025

Partnered with product management to analyse requirements, gather feedback, and support planning and estimation. Reviewed Figma designs, clarified acceptance criteria, and ensured alignment before development. Facilitated cross-team communication to resolve blockers and ensured smooth handoffs. Led the rollout of feature flags with LaunchDarkly and oversaw UI and API automation testing with Cypress to drive reliability and performance.

Senior Frontend Engineer at Circus Street (Online Learning)

November 1, 2019 - April 1, 2023

Orchestrated a seamless migration from AngularJS to a modern React + GraphQL stack, enabling incremental modernization and improved performance. Championed modularity, scalability, reusability, and accessibility, and led architectural development of hybrid runtimes to support progressive migration. Demonstrated proof-of-concepts with Sentry and Cypress to assess risk during rollout and to guide implementation strategies.

Software Engineer at Booking.com (Rentalcars.com)

January 1, 2019 - October 1, 2019

Collaborated with backend teams to define precise API contracts and shared data models. Worked in the Landing Pages team focusing on homepage and airport pages to optimize user experience. Practiced agile development, including pair programming and mobbing, and maintained strong test coverage with TDD while participating in stand-ups and retrospectives.

Frontend Developer at BuildEmpire

August 1, 2018 - December 1, 2018

Frontend Developer responsible for maintaining Thirst.io and BPP.com platforms, delivering high-performance frontends, improving stability, and implementing UX improvements.

Frontend Developer at Evoke iGaming

July 1, 2017 - March 1, 2018

Frontend Developer on multiple gaming platforms, focusing on frontend stability, performance improvements, and responsiveness across projects.

Senior Developer at EventReception.com

February 1, 2015 - December 1, 2016

Senior Developer designing full-stack web applications for weddings and events, implementing features across JavaScript, AngularJS, and PHP; improving functionality and user engagement.