Lista Combinada

About the project

Lista Combinada is a shared shopping list app for families and people living together. Each group has its own lists, with membership controlled through invitations.

Problem

Shopping items get mixed into other conversations in messaging apps, making them difficult to track. A household needs a central list that members can update and that only invited people can access.

Solution

The app organizes lists by group and lets members follow changes. Invitations specify an access role and expiration date, distinguishing group management from shopping participation.

My role

I developed the group and permission models, database security rules and invitation system. I also implemented barcode scanning, reports and the interface, and managed the app’s release.

Key features

• Shared shopping lists by group
• Invitations with an access role and expiration date
• Categorized items with additional details
• Barcode scanning to add items
• Consumption reports
• Free and premium features

Architecture and technical decisions

The app uses React Native, Expo and TypeScript, with Firebase for data storage.

Database security rules check group membership and user roles before allowing reads or writes. Authorization is therefore enforced beyond the application’s interface.

Each invitation is stored with a token, role and expiration date. When an invitation is accepted, its expiration is checked before the user joins the group with the assigned permissions.

Technical challenges

• Enforcing role-based permissions. Security rules distinguish owners, administrators and members, keeping access control at the database level.
• Limiting invitation validity. Storing and checking expiration dates prevents old links from granting access indefinitely.

Outcome

Published on Google Play, with a dedicated landing page and privacy policy.

Technologies

React Native, Expo, TypeScript, Firebase and RevenueCat.