Josie Nelder

All work

Habitual

The app behind a UK weight-loss programme and NHS provider. I helped launch it as part of a very small team, then worked across its web and mobile apps and API.

Role
Senior Full-Stack Software Engineer
Team
Very small team
Years
2021–2025
Status
Shipped
Disciplines
  • Web
  • API
  • AI
  • Data
  • Mobile

Habitual runs a UK weight-loss programme and is an NHS provider. It's now part of HeliosX.

I built the first version of its React Native app at an agency, then Habitual hired me in-house to launch it. For nearly four years I was one of the main developers in a very small team.

  • App Store image headed “Weight loss is just the beginning”: the Habitual app’s lessons tab, opening on “Understanding the Habitual Programme and Structure”.
  • App Store image headed “See and feel your progress”: a weight chart showing total weight loss of 7.2%, above a bar chart of habits by day.
  • App Store image headed “Track daily to build healthier habits”: a daily check-in with sliders for sleep, nutrition, mood and activity.
From the App Store listing.

Full-stack work

I worked across the whole lifecycle: the initial architecture, database design in Postgres, and API design and development.

On the front end I built the web and mobile apps in React, React Native and TypeScript, and deployed and maintained them in production.

Content

The programme's content lives in a GraphQL headless CMS. I designed its content models and queried them on the web, iOS and Android alongside our own API and Postgres data.

Internal AI assistant

I built an internal chatbot grounded in Habitual's documentation, using Google Vertex AI and Gemini.