Harrison Deo · Senior Frontend Engineer · UK

I build products people actually use.

Seven years in frontend. By day I'm a Frontend UI/UX Engineer at Silvercat, a London fintech. In the evenings I look after Flex Headers, a browser extension with 8,000 users that I've run on my own since 2023.

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Work

Browser extension · 2023 to present

Flex Headers

8,000+users
4.9Chrome Web Store rating
Chrome & Firefoxopen source

In 2023 the header extension I used at work had grown slow and cluttered, and another popular one had been compromised. I wrote a replacement for my own use and put it on the Chrome Web Store.

Three years on I still maintain it alone and answer every issue and email. Recent releases added undo history and cross-device sync, which uses a merge-and-tombstone scheme so that two machines editing the same page can't overwrite each other.

More about Flex Headers Chrome Web Store Firefox Add-ons GitHub

Sim racing platform · co-built

Pitskill.io

Organised online racing for sim racers: a licence system and scheduled events. Two of us built it and we each covered the whole stack, from the React frontend to the Azure infrastructure. I'm no longer involved day to day.

React · MaterialUI · Azure

pitskill.io

Travel planner · solo build

Plan Away

A trip planning app I designed, built and run on my own: interface, backend, deployment and the bills. It is small, still live, and still getting updates.

Full-stack · solo

planaway.uk

How I work

Most of my code now starts with an agent: Claude Code on personal projects, GitHub Copilot's agent mode at work. The way I use them is fairly unglamorous.

I write the spec and the constraints before anything is generated, and I spend more time arguing with the plan than with the diff. The agent writes most of the first pass. I read every line before it ships, because I'm the one who answers for it when it breaks.

The hours that saves go on the parts that need a person: the interface, the edge cases, and replying to the people using the thing. It is what makes it possible to keep two live products running in the evenings alongside a full-time job.

About

Oct 2024 to now
Frontend UI/UX Engineer, Silvercat
A London fintech. I build the customer-facing and internal products that let the group's customers and employees do things for themselves.
Before that
Senior Developer, Next
The retailer. Much of my time went on modernising the frontend architecture.
2023 to now
Flex Headers, Plan Away
Two live products I run alone in my spare time, backend and deployment included.

Most days: React, TypeScript, Next.js, Node, Playwright and Jest, CI/CD, Docker, AWS and Azure.

Outside work I race, in a sim and occasionally for real, and spend as much time outdoors as the UK weather allows.

Contact

Roles, collaborations, or something about Flex Headers. The form goes straight to my inbox.