Specifically Clementines

Groceries is an open source and self hosted grocery shopping app, with support for web/mobile and Android / iOS.

Features:

• Supports multiple shopping lists and ability to group lists into a list group
• Lists can be shared with other users
• Updates across multiple platforms and users occur in real-time, synced immediately. Conflict resolution occurs automatically and can be viewed.
• Works offline as well, when you don't have internet connectivity. Updates are synced as soon as connectivity resumes.
• List Group support includes the ability to add items to a group of stores automatically, and then if the first store doesn't have an item, it remains on the list for the next store.
• Supports a sorted view of every store by category (aisle), so you don't have to double back in the store

For a detailed description and guided tour, please visit the project's repository.