I build, fix and run software.

I'm Julien Sansot, a senior engineer in London with 18 years of shipping web, mobile and e-commerce products, for startups and large companies alike. With AI in my workflow, I deliver in weeks what used to take months, in whatever stack you already have.

Julien Sansot, smiling slightly, in a light grey sweater against a white brick wall
Julien SansotLondon, working with teams anywhere

Who I've worked with

18 years across these industries, in teams of every size, from building alone to leading a team inside a large company.

Finance
HSBC, Funding Circle, Cleo
Health
Babylon Health
Retail and food
Marks & Spencer, Mindful Chef
Automotive
Carwow, Volkswagen
Media and education
Snicket Labs, Orange Japan, Mrs Wordsmith
Public sector and transport
Ministry of Justice, SNCF

What I can do for you

By the day for ongoing or open-ended work, or at a fixed price when the scope is clear. Whichever suits you.

BuildNew products, from nothing to real users.

  • MVPs

    From idea to a working product in front of real users in weeks, not quarters.

  • Mobile apps

    iOS and Android from one codebase, with store releases, subscriptions and push notifications.

  • Shopify and Wix apps

    Custom apps and integrations: shipping, invoicing, customs, payments, checkout logic.

  • Scraping and browser automation

    Reliable data collection and automated workflows on sites with no API, including ones protected against bots.

FixCode that exists but isn't ready.

  • Vibe-code rescue

    Your AI-built prototype works in a demo. I make it secure, tested and ready for real customers.

  • Upgrades and best practices

    Outdated frameworks, no tests, slow deploys. I bring the codebase up to date and leave good habits behind.

  • Reliability audit

    I find the errors nobody sees, set up proper error tracking and fix what matters most.

RunSoftware that has to keep working.

  • Monthly retainer

    A senior engineer on hand for maintenance, small features and upgrades, for a monthly fee.

Recent work

A meal-planning app that fills your supermarket basket

My own product, iOS and Android

Users pick recipes, the app builds one shopping list, compares prices across five UK supermarkets and then fills the basket at the chosen one automatically, logging into the user's account and handling out-of-stock items along the way.

Behind it sits a pool of automated browsers that search products, scrape prices and load carts in parallel, built to stay reliable on retail sites with serious bot protection. AI reads recipes from photos and links, and matches each ingredient to the right product.

React Native, Expo, Ruby on Rails, Playwright, LLM APIs, RevenueCat

What happens after a user picks recipes

  1. Recipes inAI reads them from photos and links.
  2. One shopping listEach ingredient matched to the right product.
  3. Prices comparedAcross five UK supermarkets.
  4. Basket filledAt the chosen supermarket, in the user's own account, out-of-stock items handled.

A partner API and portal, built from zero

UK healthcare booking platform

I designed and built the company's B2B product on my own: an API with OAuth and JWT authentication, plus a web portal for partners who couldn't integrate the API themselves. As the team grew around it, I became its tech lead. I still work with them today, keeping the whole platform current and shipping AI features such as transcribing radiology reports.

Ruby on Rails, React, TypeScript, LLM APIs

Shopify apps for Swiss merchants

Swiss e-commerce app studio

I build and maintain several custom Shopify apps used by online shops, covering shipping, customs and invoicing, with backends that handle the merchants' orders and frontends that live inside Shopify's admin.

Ruby on Rails, React, Shopify APIs

How I work

  1. Day rate or fixed price

    A day rate when the work is ongoing or still taking shape, a fixed price when the scope is clear.

  2. Your stack, your code

    I work in the tools and repository you already have, and you own everything I write.

  3. AI speed, senior judgement

    AI writes a lot of the first draft. I review every line, test it and stand behind it.

Tell me what you're building.

Based in London, working with teams anywhere.

Book a 30-minute call [email protected]

Find me on LinkedIn

Book a 30-minute call