WorryTree: a CBT app that helps people manage worry and anxiety

WorryTree is built on a well-established idea from cognitive behavioural therapy (CBT): when you notice a worry, write it down, ask whether you can do something about it, and either make a plan or consciously let it go. The method works, but only if people use it at the moment they worry, and keep using it.

The founders, Louise and Mark Stevenson, needed a development partner who could rebuild the app on a modern stack, keep the experience calm and accessible for people who may be anxious while using it, and give their team a reliable backend to grow with.

We built a cross-platform Flutter app around the core WorryTree flow (capture a worry, work through it step by step, plan or let go) plus supporting features such as reminders and a history of how worries changed over time.

The interface is deliberately quiet: generous spacing, soft motion, short sentences and large touch targets. Every step can be completed in a few taps, so the app is usable in the moment a worry appears.

Behind the app runs a NestJS API with MongoDB for user data and content, with authentication, push messaging through Firebase and documented endpoints for the WorryTree team.

• App: Flutter and Dart, one codebase for iOS and Android, with accessibility settings respected throughout.
• API: NestJS with Mongoose/MongoDB, JWT and Passport authentication, Swagger/OpenAPI documentation.
• Messaging: Firebase Admin for push notifications and reminders.
• Quality: an API collection for automated endpoint tests and separate staging and production environments.
• Privacy: minimal data collection, encryption in transit and clear data-export and deletion paths, because users share sensitive thoughts.

WorryTree's founders describe the collaboration in their own words below. The rebuilt app and API give the team a modern foundation for new features and content, and the same founders also brought us into their WorkHere project.

Building a health or wellbeing app? Read about our app development approach or compare Flutter and React Native.