Data Sync Alternatives: Offline vs. Online Solutions

Data Sync Alternatives: Offline vs. Online Solutions

Ever waited to order or pay with a waiter holding their ordering device in the air for a signal? These moments show why offline-first Data Sync is essential. With more and more services relying on the availability of on-device apps and the IoT market projected to hit $1.1 trillion by 2026, choosing the right solution – particularly online-only or offline-first data sync – is more crucial than ever. In this blog, we discuss their differences and highlight common Data Sync alternatives.

What is Data Sync?

Data synchronization (Sync) aligns data between two or more devices to maintain consistency over time. It is an essential component in applications ranging from IoT and mobile apps to cloud computing. Challenges in data synchronization include asynchrony, conflicts, and managing data across flaky networks.

Data Sync vs. Data Replication

Data Synchronization is often confused with Data Replication. Nevertheless, they serve different purposes:

  • Data Replication: A unidirectional process (works in one direction only) that duplicates data across storage locations to ensure availability and prevent loss. It is simple but limited in its application, and efficiency, and lacks conflict management.
  • Data Synchronization: A bidirectional process that harmonizes all or a subset of data between two or more devices. It ensures consistency across devices and entails conflict resolution. It is inherently more complex but also more flexible.

Online vs Offline Solutions: Why Offline Sync Matters

Online-only synchronization solutions rely entirely on cloud infrastructure, requiring a stable internet connection to function. While these tools offer simplicity and scalability, their dependency on constant cloud connectivity brings limitations: Online Data Sync solutions cannot guarantee response rates and their speed varies depending on the network. They do not work when offline or in on-premise settings. Using an Online Sync solution often entails sharing the data and might not comply with data privacy requirements. So, do read the terms and conditions.

Offline-first solutions (offline Sync) focus on local data storage and processing, ensuring the app remains fully functional even without an internet connection. When a network is available, the app synchronizes seamlessly with a server, the cloud, or other devices as needed. These solutions are ideal for on-premise scenarios with unreliable or no internet access, mission-critical applications that must always operate, real-time and high-performance use cases, as well as situations requiring high data privacy and data security compliance.

A less discussed, but in our view also relevant point, is sustainability. While there might be exceptions depending on the use case, for most applications offline-first solutions are more resourceful and therefore more sustainable. If CO2 footprint or battery usage is of concern to you, you might want to look into offline-first Data Sync alternatives.

Now, letโ€™s have a look at current options:

Data Sync Alternatives

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Solution Company Type Offline Support Self-hosted Sync Decentralized Sync Database Type of DB OS/Platforms Languages Open-Source Component License Other Considerations Country
Firebase Google
 (Firebase was acquired by Google in 2014)
Online Local cache only, no persistence, syncs when online Cloud: Firebase Realtime Database; Edge: Only caching, no DB (called Firestore) Document store iOS, Android, Web Java
JavaScript
Objective-C
Swift
Kotlin
C++
Dart
C#
Python, Go, Node.js
proprietory Tied to Google Cloud, requires internet connectivity 🇺🇸
Supabase Supabase Online Limited Cloud DB: PostgreSQL Relational document store Primarily a cloud solution JavaScript/TypeScript
Flutter/Dart
C#
Swift
Kotlin
Python
Apache License 2.0 Supabase is mainly designed as a SaaS, for use cases with constant connectivity 🇸🇬
ObjectBox Sync ObjectBox Offline-first In development ObjectBox Object-oriented embedded NoSQL DB Android, Linux, Ubuntu,
Windows,
macOS, iOS,
QNX, Raspbian,
any POSIX system really,
any cloud (e.g. AWS/Azure/Google Cloud),
bare metal
C
C++
Java
Kotlin
Swift
Go
Flutter / Dart
Python
DB: Open source bindings, Apache 2.0, closed core Highly efficient (saves CPU, Memory, battery, and bandwidth); fully offline-first, supports on-premise settings, 100% cloud optional 🇩🇪
Couchbase (Lite + Couchbase Sync Gateway) Couchbase (a merger of Couch One and Membase) Online The CE Sync is a bare minimum and typically not usable; Self-hosted Sync with Couchbase Servers is available as part of their Enterprise offering ✅ as part of the Enterprise offering; gets expensive quickly Edge: Couchbase Lite; Server: Couchbase Multi-model NoSQL document-oriented database Couchbase Lite: iOS, Android, macOS, Linux, Windows, Raspbian and Raspberry Pi OS

Couchbase Sync Gateway: Red Hat Enterprise Linux (RHEL) 9.x, Alma Linux 9.x, Rocky Linux 9.x, Ubuntu, Debian (11.x, 12.x), Windows Server 2022
.Net
C
Go
Java
JavaScript info
Kotlin
PHP
Python
Ruby
Scala
Couchbase Lite is available under different licenses; the open source Community Edition does not get regular updates and misses many features especially around Sync (e.g. it does not include Delta Sync making it slow and expensive) Typically requires Couchbase servers, quickly gets expensive 🇺🇸
MongoDB Realm + Atlas Device Sync MongoDB
 (Realm was acquired by MongoDB in 2019)
Offline-First Cloud-based sync only Cloud: MongoDB, Edge: Mongo Realm DB MongoDB: NoSQL document store; RealmDB: Embedded NoSQL DB MongoDB: Linux
OS X
Solaris
Windows
Mongo Realm DB:
Android, iOS
more than 20 languages, e.g. Java, C, C#, C++ MongoDB changed its license from open source (AGPL) to MongoDB Inc.’s Server Side Public License (SSPL) in 2018. RealmDB is open source under the Apache 2.0 License. The Data Sync was proprietary.  Deprecated (in Sep 2024); End-of-life in Sep 2025; ObjectBox offers a migration option 🇺🇸

While SQLite does not offer a sync solution out-of-the-box, various vendors have built something on top, or integrated with SQLite giving them offline persistence.

Key Considerations for Choosing a Data Sync Solution

When selecting a synchronization solution, consider:

  1. Connectivity Requirements: Will the application function in offline environments; how will it work with flaky network conditions; how is the user experience when there is intermittent connectivity?
  2. Data Privacy & Security: How critical is it to ensure sensitive data remains local? Data compliance? How important is it that data is not breached?
  3. Scalability and Performance: What are the expected data loads and network constraints? How important is speed for the users? Is there any need to guarantee QoS parameters? How much will the cloud and networking costs be?
  4. Conflict Resolution: How does the solution handle data conflicts?
  5. Delta Sync: Does the solution always synchronize all data or only changes (data delta)? Can a subset of data be synchronized? How efficient is the Sync protocol (affecting costs and speed)?

The Shift Towards Edge Computing

The trend toward Edge Computing highlights the growing preference for offline-first solutions. By processing and storing data closer to its source, Edge Computing reduces cloud dependency, enhances privacy, and improves efficiency. Data synchronization plays an important role in this shift, ensuring seamless operation across decentralized networks.

Offline and online synchronization solutions each have their merits, but the rise of edge computing and data privacy concerns has propelled offline Sync to the forefront. Developers must assess their application’s unique requirements to select the most appropriate synchronization method. As the industry evolves, hybrid and offline-first solutions are going to dominate, offering the best balance of functionality, privacy, and performance.

Flutter databases –  Hive, ObjectBox, sqflite, Isar and Moor (e.g. Drift, floor)

Flutter databases – Hive, ObjectBox, sqflite, Isar and Moor (e.g. Drift, floor)

Flutter, the renowned cross-platform mobile framework, has been gaining immense popularity among developers worldwide. In 2024, Flutter had over 1 million monthly active developers, was behind nearly 30% of new iOS apps, and continued to be the most popular framework for cross-platform development. Dart, the programming language behind Flutter, was first released in 2011 and already made it to spot 28 on the Tiobe index as of February 2025.

This growth comes from a strong community, with more than 1,400 contributors, 10,000 package publishers, and over 50,000 available packages. As the Flutter community expands, the demand for efficient Flutter databases is also increasing. Developers now have access to a range of Flutter database options that cater to various needs and preferences.

In this article, we’ll focus specifically on local storage solutions, as these are essential for enabling offline functionality, improving performance, ensuring data persistence, enhancing data privacy and security, and supporting edge computing capabilities. Furthermore, local data storage is needed to promote sustainability. Let’s dive into the current local database landscape for Flutter and compare the most popular options.

Flutter databases / Flutter Dart data persistence

While the database market is huge and dynamic,  there are only few options to choose from if you are a Flutter / Dart app developer. Before we dive into the Flutter database options, advantages and disadvantages, we’re taking a very quick look at databases to make sure, we share a common ground. 

What is a database?

A database is a piece of software that allows the storage and systematic use of digital information, in other words: data persistence. As opposed to mere caching, data is reliably stored and available to work with unless actively deleted. A database typically allows developers to store, access, search, update, query, and otherwise manipulate data in the database via a developer language or API. These types of operations are done within an application, in the background, typically hidden from end users. Many applications need a database as part of their technology stack. The most typical database operations are CRUD: Create, Read, Update, Delete.

What are the major types of databases?

There are many types of databases. For our purpose, the most important differentiations are non-relational (NoSQL) versus relational databases (SQL), cloud databases versus edge databases, and maybe embedded versus in-memory. However, databases can be further distinguished by additional criteria e.g. the data types they support, or the way they scale โ€“ and definitions can vary.

What is an ORM?

An Object relational Mapper (ORM) is not a database. We’re bringing this up mainly, because we see it confused often. It is a layer that sits on top of a database and makes it easier to use. This is typically especially relevant when the database is a relational database (SQL) and the programming language used is object-oriented. As noted above, Dart is an object-oriuented programming language.

The Flutter local data persistence landscape

There are several Flutter databases that provide offline support, offering the ability to store and access data locally even without an internet connection. Here are some of the notable options:

  • Hive is a lightweight key-value database written in Dart for Flutter applications, inspired by Bitcask.
  • ObjectBox DB is a highly performant lightweight NoSQL database with an integrated Data Sync. It stores objects.
  • sqflite is a wrapper around SQLite, which is a relational database without direct support for Dart objects. 
  • Drift is a reactive persistence library for Flutter and Dart, built ontop of SQLite. 
  • Floor is another ORM on top of SQLite.

 

What is the best offline Flutter Dart database?

This of course depends… Make up your own mind with the following comparison matrix as a starting point. Note: With very few options to choose from, the following overview is sometimes a bit like comparing apples ๐ŸŽ and pears ๐Ÿ.

Data persistence Description Primary Model Data Sync Language License Fun Fact "Headquarter"
Drift ORM on top of SQLite relational โŒ SQL SQLite is public domain, Drift is MIT Formerly known as Moor ๐Ÿ‡ฉ๐Ÿ‡ช
Floor ORM on top of SQLite relational โŒ SQL SQLite is public domain, floor is Apache 2.0 Developed by a mobile app agency, not an individual author  ๐Ÿ‡ณ๐Ÿ‡ฑ
Isar Lightweight NoSQL database NoSQL โŒ Dart Apache 2.0 Also the author of Hive - both libs are not maintained anymore ๐Ÿ‡ฉ๐Ÿ‡ช
Hive Predecessor of Isar NoSQL โŒ Dart Apache 2.0 Also the author of Isar - both libs are not maintained anymore ๐Ÿ‡ฉ๐Ÿ‡ช
ObjectBox Lightweight NoSQL database with integrated Data Sync NoSQL โœ… Dart Bindings are Apache 2.0 It is used in BMW cars ๐Ÿ˜ฎ ๐Ÿ‡ฉ๐Ÿ‡ช
Realm NoSQL database acquired by Mongo DB in spring 2019, Flutter binding came in 2023, now deprecated NoSQL Deprecated, End of life in Sep 2025; closest substitute is ObjectBox Dart Apache 2.0 Originally Realm was developed in Denmarkโ€ฆ MongoDB stopped Realm support and the Sync is deprecated ๐Ÿ‡บ๐Ÿ‡ธ
Sembast NoSQL database, fully document-based NoSQL โŒ Dart BSD-3-Clause Also the author of SQFlite ๐Ÿ‡ซ๐Ÿ‡ท
sqflite SQLite plugin for Flutter relational โŒ SQL SQLite is public domain, sqflite lib is MIT Not an ORM ๐Ÿ‡ซ๐Ÿ‡ท
 
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Flutter Database performance benchmarks

As with any benchmark, you need to take a look at the details. We take benchmarking very serious and strive to get accurate results. Therefore, we also always open source the benchmarking code and encourage you to check it out. If you note anything that does not even out in your oppinion, do let us know. We have a long history of updating and improving our benchmarks continually and are happy to take any recommendations.

Performance Benchmark Test Setup

We used an Android 10 device with a Kirin 980 CPU to run the benchmarks as a Flutter app. The app executed all operations (ops) in batches of 10.000 objects. Each batch formed a single transaction. We ran each test 50 times. The results you see in the diagram are averages across all runs. We set it up that way to ensure that neither the Virtual Machine warmup during the first run nor the garbage collections affect the overall result significantly. 

Flutter Databases CRUD Performance Results

Summary of the Flutter Dart DB Benchmarks

Hive and ObjectBox clearly outperform sqflite across all CRUD operations. The results show ObjectBox performing with up to 70 times the speedup for create and update operations. With regards to comparing Hive and ObjectBox, the results vary more. Hive can be faster at reading objects than ObjectBox. However, strictly speaking it’s not a fair comparison, because in Hive, the high read numbers result from Dart objects already cached in memory. If the objects are fetched using the async API from disk, the numbers drop by factor 1000.

Drift and Floor were not part of the benchmarking as they are ORMs. However, it is very likely they will perform similarly to sqflite, reflecting primarily the performance of SQLite.

Flutter Data persistence – Conclusion

Recently, the Flutter database landscape has experienced significant growth and diversification. With Flutter’s increasing popularity, developers now have a number of database options available. In this article, we focused on the best local databases, comparing their features in a comprehensive matrix, and showcasing performance benchmarks. In the end, the best choice depends on the specific needs of each project. The Flutter database landscape in 2025 is a thriving ecosystem, continuously evolving to meet the changing needs of Flutter app development. One upcoming change that we can see is the rise of vector databases for AI. So, we encourage you to keep an eye on the lively market of Flutter databases not to miss any important updates.

If you want to get started learning how to use a database, we suggest you check out this video tutorial series that teaches you how to build a Flutter app with ObjectBox from scratch.