MongoDB no longer supports Atlas Device Sync and Atlas Device SDKs. Here’s what to know about migrating to Couchbase Mobile.
The mobile database platform landscape has dramatically changed. As of today, Sept. 30, 2025, MongoDB has officially ended its mobile support, specifically Atlas Device Sync and Atlas Device SDKs (formerly known as Realm).
Developers who have relied on these MongoDB products for data synchronization in their mobile and IoT apps must now transition to a different mobile solution. Many organizations facing this situation might assume it will require building custom sync logic or integrating a third-party service to handle data synchronization, neither of which is a trivial task.
Thankfully, the Couchbase Mobile alternative not only matches the requirements of your Realm-based apps, but also delivers new capabilities that make your apps even better.
Why mobile support matters
Before we give some next steps for how to migrate off Realm, it is important to understand how critical mobile development has become.
Today’s consumers demand mobile application experiences that are always fast, available, personalized, and engaging. Meeting these expectations are critical for driving adoption and sustaining growth. Falling behind comes with the risk of users abandoning the app altogether.
But guaranteeing a fast, always available, experience becomes a challenge if the database that powers the app runs only in the cloud. Because mobile users are constantly moving in and out of network coverage, if they lose the connection, the mobile app slows or fails outright.
To maintain a great user experience in disconnected environments, and areas with unreliable internet access, mobile developers often turn to mobile database platforms. These solutions combine a cloud database with an embedded, on-device, database that operates directly within the application.
The cloud database and embedded database remain consistent through data synchronization when network connectivity exists, and when the network slows or is interrupted, the local database ensures that the app remains fast and available. By processing data locally, these platforms eliminate the need for an internet connection to a distant cloud database; it instead uses the local data to power the app.
It’s important to note that the cloud is still crucial as a central data aggregation point for mobile apps. This is why a fully integrated enterprise-class cloud database with built-in data synchronization are such critical components for a mobile database platform, as nearly every app needs a scalable backend and the ability to share data between devices and the cloud for consistency.
As you can imagine, because of these requirements, many mobile application developers rely on mobile database platforms to ensure their apps are fast and available without requiring an internet connection.
Comparing Couchbase Mobile to MongoDB Atlas Device Sync/Atlas Device SDKs
Now that developers need to make a move, let’s examine how MongoDB’s deprecated mobile support compares to our mature and innovative mobile database platform, Couchbase Mobile.
Both platforms provide a cloud NoSQL database backend, embedded data persistence for mobile apps, and data synchronization capabilities, but that’s where the overlap ends. At a feature level, there are many differences between the two platforms. Here are a few of the major distinctions:
Schema flexibility
Atlas Device SDK was object oriented, which had its advantages, but it also required a schema for modeling relationships, creating rigidity that increased application complexity.
Couchbase Mobile is schemaless. It’s a classic JSON document database, which makes it more flexible. Developers don’t have to worry about rigid schemas when doing things like adding new fields and indexes. This can make application upgrades faster, easier and more efficient.
SQL support
Atlas Device SDKs used a proprietary query language and syntax that lacked built-in support for joins and aggregations. This forced developers to work around these limitations in code.
Couchbase Mobile supports SQL from the cloud database to the on-device database. This means developers use the same queries across application ecosystems. The familiarity of SQL also allows them to use their existing skills, making Couchbase easy to adopt.
Vector search
MongoDB only supports vector search in Atlas, making it dependent on internet access to work. This means if there’s no internet, there’s no vector search.
Couchbase Mobile supports vector search both in its cloud database platform Capella and in Couchbase Lite running on the device. This enables offline-first edge AI capabilities, helping to future-proof applications and add AI features.
Data sync
MongoDB’s sync solution did not support peer-to-peer sync. This meant it couldn’t sync without an internet connection to Atlas, and it did not support custom conflict resolvers.
Couchbase Mobile offers peer-to-peer sync. This enables data sync to happen via peer-to-peer access between local devices without requiring an internet connection or central cloud control point. Additionally, developers can rely on Couchbase Mobile to create customized conflict resolution policies.
Device Platform Support
Atlas Device Sync primarily supported mobile device platforms such as Android, iOS, React Native and .NET.
Couchbase Mobile supports all of the above platforms, and offers the C API, allowing developers to embed data processing to resource-constrained IoT devices on single-board computers like Arduino and Raspberry Pi.
To learn more, this matrix provides a detailed comparison of Couchbase Mobile and MongoDB Atlas Device Sync/Atlas Device SDKs features. This GitHub guide also compares Atlas Device SDK and Couchbase Lite functionalities, including Android, .NET, Objective-C and Swift.
Resources for moving to Couchbase Mobile from MongoDB Atlas
Database migrations often come with hurdles. Unexpected issues can arise even with the most carefully thought out plans. If you are moving from MongoDB Atlas Device Sync/Atlas Device SDK to Couchbase Mobile, there are a host of resources to help streamline the process and make it as smooth as possible.
Read our in-depth migration guide that digs into the technical considerations and approaches for migration, including data modeling, data and application migration. It’s an essential read for developers migrating from MongoDB Atlas Device SDK to Couchbase Mobile.
The Director of Software Engineering and Compliance from cloud-based point-of-sale (POS) technology provider Quantic explains why the company chose Couchbase Mobile over Realm in this webcast.
This video with Couchbase partner MOLO17 details how its real-time hybrid data integration platform GlueSync helps developers easily move data from MongoDB Atlas to Couchbase Capella for Couchbase Mobile migrations.
As if that weren’t enough, check out these in-depth video tutorials on how to migrate from Atlas Device SDKs to Couchbase Mobile. They are must-see assets for mobile developers making the switch.
Conclusion
Couchbase Mobile is a developer-friendly, AI-ready mobile app database that uniquely offers SQL support, built-in sync, and vector search from cloud to edge and IoT devices. Our mobile capabilities are considered to be one of our greatest strategic differentiators. That’s why hundreds of customers use the platform for their high-scale mobile apps, including PepsiCo, Emirates, Lotum and AutoCrib.
With over a decade of experience supporting mission-critical mobile applications, we remain committed to being a leader in mobile application development, and will continue to invest in providing innovative capabilities for powering offline-first mobile and IoT apps.
Learn more about how customers are using Couchbase to quickly and affordably build always-on mobile applications. You can also sign up to use Capella App Services FREE today.
