list of databases that can be used in Flutter apps with free data storage:

Here's a list of databases that can be used in Flutter apps with free data storage:

1. Firebase Realtime Database - 1GB storage for free 

2. Firebase Cloud Firestore - 1GB storage and 50k reads and 20k writes per day for free 

3. AWS Amplify DataStore - 5GB storage and 250k sync operations per month for free 

4. MongoDB Atlas - 512MB storage for free 

5. Back4App - 1GB storage and 10k API requests per month for free 

6. FaunaDB - 5GB storage and 100k read and write operations per month for free

 7. Supabase - 10GB storage and 10k API requests per month for free 

8. Heroku Postgres - 10k rows and 400MB storage for free 

9. Google Cloud Firestore - 1GB storage, 50k reads and 20k writes per day for free 

10. DigitalOcean Managed Databases - 250MB storage for free Please note that the free storage and usage limits may vary over time and depend on the provider's policies.