Realm Mobile Database

Build better apps, faster. Realm’s open source database helps mobile developers build offline-first apps in a fraction of the time. SDKs for Swift, Objective-C, Java, Kotlin, C#, and JavaScript.

Build better apps, faster.

With a flexible, object-oriented data model, Realm’s Database is simple to learn and reflects the way you already code. And because it was built specifically for mobile, apps built on Realm are reliable, performant, and work cross-platform.

Fast to Get Started

Object-oriented data model is simple to learn and use. Live objects keep your data up-to-date without additional code.

Designed for Offline Use

Build a reliable, performant app with a datastore built for mobile. Apps work offline and optimize your use of bandwidth, CPU, and battery power.

Security Made Simple

Data is encrypted in-flight or at-rest. The Realm Mobile Database can keep even the most sensitive data secure.

Why use the Realm Database?

100k+ developers have chosen to build their apps using Realm’s open source database. See why millions of people use apps built on Realm every day.


Use a single database to build all your apps, on any major platform. Realm is designed for use on iOS and Android, with cross-platform data modeling made easy.

Offline First

Realm’s lightweight, fully-featured datastore is embedded directly on the device. Read and write data locally, to build apps that work even when users are offline.

Highly Performant

Even large data loads and complex queries seem instant with Realm. Build a performant app that’s always up-to-date with new data.

Reactive Architecture

Realm’s unique live objects ensure that data updated anywhere is automatically updated everywhere. Connect your UI to Realm, and data changes will appear automatically.

Safe Threading

Access the same data concurrently from multiple threads, with no crashes.

Fully Encrypted

Secure your data with transparent encryption and decryption.
Trusted by Fortune 500 mainstays, innovative startups, and #1-ranked app store successes

Get Started with Realm

Create your first app

Build a collaborative task tracker app with Realm and Realm Sync.

See Realm Sync

Learn about MongoDB Realm’s data synchronization service, to seamlessly sync your data from the client-to-the-cloud.

Looking for legacy docs?

If your app is built on a past version of Realm, access the legacy docs here.