Storing Data Offline with Flutter

There are some options of databases available for storing data offline in your Flutter app and selecting the right one is crucial for the success of your project. In this article, I will address the main options that you can consider to use on your project. I've selected three of them to clarify the situations in which each one can be a viable choice. In this article, I won't provide detailed implementation instructions for each one, as there is an abundance of materials and documentation available for more comprehensive guidance and understanding.

Firestore Database

Firebase Firestore is a cloud-hosted, NoSQL database provided by Google as part of the Firebase platform. Firestore is designed to store and synchronize data for web, mobile, and server applications. It is a flexible and scalable database solution that offers real-time synchronization and offline support (and that's great), making it well-suited for building responsive and collaborative applications.

In my experience, the best aspect of using Firestore is its ability to automatically handle the integration of offline data. In other words, if your phone goes offline for any reason, Firestore will save the data in an internal database and integrate it once the internet connection is restored.

The bad news is that if you plan to scale this application for a large number of users, you must consider that this service may become paid. Check out Firebase pricing.

Hive

Hive is a NoSQL, key-value database library for Flutter and Dart, which is specifically designed for mobile and web applications. It's a popular choice for local data storage and management in Flutter apps due to its simplicity and performance. If you are looking for a lightweight, high-performance, easy-to-use, and versatile local database solution, Hive can be your choice.

If your application must be offline first, I strongly recommend this one. It's a very customizable database, easy to save simple and complex data with a large number of users. In one of the projects that I worked on, I had to store a bunch of events offline and five to five minutes send these stored data to the server via REST API. So I decided to save each event in a box (which is like a table) as a Map, doing a "toJson" in each record, and then trying to send data to the server recovering this map parsing to a JSON string. It was a very easy and useful solution for that opportunity.

SQLite

SQLite is a widely used open-source, embedded relational database management system (RDBMS). Unlike traditional database management systems like MySQL, PostgreSQL, or Oracle, SQLite is not a standalone server-client model but is instead embedded directly into the application that uses it.

The most used Flutter plugin to work with SQLite is sqflite.

In my opinion, one of the biggest advantages of SQLite is the portability that it can provide for your application. Once that it's an internal library, which means there is no separate database server, your database file is simply a file on the file system, making it highly portable. So you can move the database file between systems easily.

Conclusion

I didn't talked about other options like Isar and Objectbox but they are similar to Hive and are Non-SQL also, both are good options too.

Each project deserves time of reflection before making the decision which database is better for your application and the explanation of these three options mentioned in this article can guide you to make the right choice to use on your project.