Senior Software Engineer & Technical Lead

Hands‑on technical leadership across complex Next.js and React platforms, digital transformations, technical SEO, performance, migrations and platform architecture.

Dataffirm

I'm John, an award‑winning independent software engineering specialist based in sunny cloudy Brighton, UK.

I am a friendly and enthusiastic senior engineer and technical leader backed by over twenty‑three years of hands‑on experience.

I help teams and clients design, build and improve websites, applications and web platforms, pairing architecture, delivery judgement and hands‑on TypeScript, React, HTML and CSS.

My portfolio is diverse; I work with global clients, solving real-world problems, including:

leading the headless replatforming of a much loved chain of restaurants, modernising its UK & Ireland web estate;
engaging businesses, politicians, academics, and world leaders to shape global agendas;
leading the modernisation of the online portfolio of one of Britain's largest airlines;
... and optimising the online ordering system of Brighton's last independent milkman.

More about me

Featured Projects

How I Usually Help

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Previous Clients

John Lewis logo
The BBC logo
Gov.uk logo
HSBC logo
British Airways logo
eBay logo
Condé Nast Britain logo
Nintendo logo
Lotus Cars logo
Team GB logo
Marvel Comics logo
London Philharmonic Orchestra logo
Bosch (BSH Group) logo
Volkswagen logo
Cisco logo
Activision logo
London 2012 Olympics and Paralympics logo
Microsoft logo
Apple logo
Gatsby logo
Plex TV logo
LEGO logo
Selfridges logo
The World Economic Forum logo
Made by Many logo
AND Digital logo
IMG Licensing logo
Disney logo
Boohoo Group logo
Debenhams.com logo
The Rolling Stones logo
Wreel Agency logo
Polestar logo
MOSCOT logo
Virgin Atlantic logo
American Express logo
The Guide Dogs for the Blind Association logo
Style.com logo
Macmillan Education logo
Zara logo
Boeing logo
Valtech logo
McCann Manchester logo
Warwick Acoustics logo
Nando’s logo
Virgin Active logo

"
John Kavanagh was always articulate, willing to speak his mind, helpful and always did an amazing job ‑ he clearly takes immense pride in his work (and rightly so!). His attention to detail and perfectionist attitude helped produce a product that we could all be proud of."
Howell Lee Head of Business Analysis
"
John Kavanagh is one of the most open‑minded developers I have ever worked with. His appreciation of great creative work, his enthusiasm and 'anything is possible' attitude is always a breath of fresh air. He is always super efficient and effective, combining a great work ethic with immense talent."
Mike Etheridge Creative Direction + Design
"
John Kavanagh's biggest strength is his ability to deal with conflicting priorities in high‑pressure situations. Along with his excellent development skills, John's ability to manage difficult stakeholders and requirements is one of the key reasons that the projects he led were completed on time without too many problems."
Devrim Ersanli Senior Front‑end Developer
"
I've worked with John Kavanagh several times, and can fully recommend his services as a front‑end web developer to anyone. He is a strong JavaScript programmer, and has thorough knowledge of cross‑platform HTML/CSS development. Always punctual, very friendly and importantly knows how to get the job done on time, maintaining a keen eye for professional detail."
Christian Duncan Technical Lead
"
John Kavanagh is an 'above and beyond' front‑end developer. By that, a task could be assigned to John and he would complete it effectively, but more than that, if involved at the beginning of the process, he would add so much more value to the project in way of ideas, solutions, process, search optimisation, user experience and so forth."
David Mannheim Founder & CEO
"
John Kavanagh is a fantastic developer with all the skills one would want in a lead developer. He's done a superb job on all tasks and has been a great resource within the company. Exceptionally knowledgeable, self‑motivated, and a great team player. I would certainly work with John again!"
Adam Millington Front‑end Developer

Availability

I am currently leading a new digital transformation engagement. I have limited availability for selected consulting and engineering delivery from September 2026.

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