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Greg Kemp
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From fusion
to full stack.

Greg Kemp in sunglasses, holding a small tortoise
Rescuing a tortoise from a road in Croatia.

I'm Greg Kemp, a senior full-stack engineer in Budapest. I trained as a mechanical engineer and worked on fusion at ITER before software took over. For eleven years I've been building products for brands like Primark, SuperDry and Pepco, and these days I spend most of my time designing and building TariffTel 2.0.

See my work Get in touch

How I got here

Not a straight line. Physics, a climbing injury and a lot of software, in roughly that order.

  1. 2007–2013

    Cardiff

    A mechanical engineering degree, and my first proper taste of the maths I still like most.

  2. Internship

    ITER, Barcelona

    Calculating forces on the first wall, the part of a tokamak that faces the plasma. One of the more abused pieces of metal in the universe.

  3. 2013

    Climbing instructor

    A year teaching climbing, until shoulder surgery grounded me and I tried programming to fill the time.

  4. 2014

    First dev job

    Joined CORE (UK) Ltd as a junior developer. Eleven years on I'm still there, now as senior developer and architect.

  5. 2018–2019

    MSc Fusion Energy, York

    A thesis on QED radiation reaction in high-energy laser–plasma interactions. I came out loving the physics.

  6. Now

    Senior developer and architect

    Designing and building TariffTel 2.0 with a small team. Mostly brand new work, which is the fun kind.

What I build at work

Eleven years at CORE (UK) Ltd, now TariffTel, building customs classification software: the systems large companies use to work out how every product they sell is classified at the border. Clients have ranged from Primark to Triumph Motorcycles.

  1. 2014–2017 Junior developer
  2. 2017–2022 Developer
  3. 2022–present Senior developer and architect

2022–present

TariffTel 2.0

Customs classification, redesigned and rebuilt from the ground up.

A new product rather than a port of the old one, now used by large retailers like Pepco. It comes in two parts, and while I work mainly on TTVerified, it's a small team and we all do a bit of everything.

TTVerified
For businesses that need classifications they can rely on, backed by data curated by our in-house customs team.
TTExplore
For anyone. AI suggests a classification, with a score for how likely it is to be right.

.NET 8/10, Angular 19, Clean Architecture, CQRS, SignalR, Microsoft Entra ID, Azure

Master Data Management System

A new .NET 10 system with a custom CQRS dispatcher in place of MediatR, and Dapper wherever queries need to be fast.

.NET 10, Angular 19, Tailwind, Dapper

Customs Connect

Customs declaration software for Primark. I rebuilt version 2 as a fully serverless app that plugs into classification and supply-chain systems.

Azure Functions, .NET

LEAF

Sustainability reporting that traces where garment fibres come from, for the SCAP scheme. Built from scratch with a small team and adopted by Primark.

ASP.NET MVC, Azure Functions

TariffTel Essentials and Premium

A customs classification web app for individuals, then its business sibling, which I built single-handedly.

Angular, .NET

What I build for fun

Side projects are where I try the stacks I don't get to use at work. One of them is turning into a real product.

Free early access

Dayworks

Brief the day. Book the hours. Sign off the diary.

Site paperwork for UK construction teams. A friend of mine is a site engineer, and I'm building this with his input to fix a problem he has every day: the same hours typed up again and again across spreadsheets, labour sheets and site diaries.

With Dayworks the team is briefed in the morning, hours are booked on a phone through the shift, and the diary is signed off and locked at the end of the day. The labour sheets and weekly returns write themselves. I'm building it on my own, it's open for early access now, and the first company is getting set up for a trial.

Next.js, Supabase, Drizzle, Tailwind, Resend, Vercel

Visit dayworks.build

DevSync

A code snippet manager for teams, with roles, full-text search, GitHub sign-in, invitations and paid tiers.

Next.js 16, PostgreSQL, Prisma, NextAuth

CodeMop

AI code review. It hooks into GitHub pull requests and suggests improvements automatically.

Python, FastAPI, PostgreSQL

EV Route Optimizer

Plans electric car journeys around charging stops, on an interactive map.

Node.js, React 19, Leaflet, GraphHopper, OpenChargeMap

EV Fleet Platform

A .NET fleet API paired with a Python engine that solves vehicle routing with Google OR-Tools.

.NET 8, Python, Flask, OR-Tools, Docker

Outside work

  • Climbing
  • Caving
  • Guitar
  • Machine learning

Say hello

Hiring, collaborating, or curious about any of the above? Send a message, or email me at greg@kempgt.com .