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Realm Blog
Articles by the Realm team and community


When building a mobile app, there’s a good chance that you want it to pull in data from a cloud service-whether from your own or from a third party. While other technologies are growing (e.g., GraphQL and MongoDB Realm Sync), REST APIs are still prevalent.

It’s easy to make a call to a REST API endpoint from your mobile app, but what happens when you lose network connectivity? What if you want to slice and dice that data after you’ve received it? How many times will your app have to fetch the same data (consuming data bandwidth and battery capacity…


In the previous post in this series, we saw how to migrate your Realm data when you upgraded your iOS app with a new schema. But, that only handled the data in your local, standalone Realm database. What if you’re using MongoDB Realm Sync to replicate your local Realm data with other instances of your mobile app and with MongoDB Atlas? That’s what this article will focus on.

We’ll start with the original RChat app. We’ll then extend the iOS app and backend Realm schema to add a new feature that allows chat messages to be tagged as high priority…


Murphy’s law dictates that as soon as your mobile app goes live, you’ll receive a request to add a new feature. Then another. Then another.

This is fine if these features don’t require any changes to your data schema. But, that isn’t always the case.

Fortunately, Realm has built-in functionality to make schema migration easier.

This tutorial will step you through updating an existing mobile app to add some new features that require changes to the schema. …


This tutorial is focused on those developers who have a Realm application and want to create an alert monitoring system that sends an SMS every time a new error appears in our application.

Currently, there are three ways to access the logs of our system:

  1. Through the Logs section of our graphical interface: From here we will be able to access the logs and we will be able to filter between the different origins, dates, etc.
  2. Using the Admin API Rest: this will allow us to request the logs of an application programmatically by accessing the logging endpoints of the…


What is Jetpack Compose?

As per Google, “Jetpack Compose is Android’s modern toolkit for building native UI. It simplifies and accelerates UI development on Android. Quickly bring your app to life with less code, powerful tools, and intuitive Kotlin APIs”.

In my words, it’s a revolutionary declarative way of creating (or should I say composing 😄) UI in Android using Kotlin. Until now, we created layouts using XML and never dared to create via code (except for custom views, no choice) due to its complexity, non-intuitiveness, and maintenance issues.

But now it’s different!

What is Declarative UI?

You know, imperative is like how you do something, and declarative…

Photo by Jexo on Unsplash

Hello Everyone, I am Henna :) and this is my 3rd article in the MongoDB Realm Sync series.

So far in the 2 articles, we have learned to create:

  1. Getting Started with MongoDB Realm and Google Authentication
  • MongoDB Realm Account
  • Organizations and Projects
  • Cluster Tier and Configuration
  • Realm App on UI
  • Google Authentication in Android App

2. Getting Started with Realm Sync for Android Application

  • Sync Configuration on UI
  • Understanding Development Sync Mode
  • NoteKeeper Android App with Sync

In this article, you will learn more about Sync Modes and how to implement Sync and create schemas when you already have…


Embedding Apple Maps and location functionality in SwiftUI apps used to be a bit of a pain. It required writing your own SwiftUI wrapper around UIKit code-see these examples from the O-FISH app:

If you only need to support iOS14 and later, then you can forget most of that messy code 😊. If you need to support iOS13-sorry, you need to go the O-FISH route!

iOS14 introduced the Map SwiftUI view (part of Mapkit) allowing you to embed maps directly into your SwiftUI apps without messy wrapper code.

This article shows you how to embed Apple Maps into your app…

Welcome back! We really appreciate you coming back and showing your interest in Realm. This is a follow-up article to Introduction to Realm for Android. If you haven’t read that yet, we recommend you go through it first.

This is a beginner-level article, where we introduce you to MongoDB Realm Sync. As always, we demonstrate its usage by building an Android app using the MVVM architecture.


You have created at least one app using Android Studio.

What Are We Trying to Solve?

In the previous article, we learned that the Realm SDK is easy to use when working with a local database. …

Didn’t get a chance to attend the Easy Realm JWT Authentication with CosyncJWT Meetup? Don’t worry, we recorded the session and you can now watch it at your leisure to get you caught up.

In this meetup, Richard Krueger, CEO Cosync, will focus on the benefits of JWT authentication and how to easily implement CosyncJWT within a Realm application. CosyncJWT is a JWT Authentication service specifically designed for MongoDB Realm application. It supports RSA public/private key third party email authentication and a number of features for onboard users to a Realm application. These features include signup and invite email confirmation, two-factor verification through the Google authenticator and SMS through Twilio, and configurable meta-data through the JWT standard. …


This guide will show how to create a signing key and a JWT token to test one of the Authentication providers Realm offers.

There are two main scenarios for requiring Custom JWT Authentication.

  1. Using a third-party service authentication like Firebase, Cosync, or Auth0.
  2. Using your own custom authentication to sign and validate JWT tokens.

This guide will focus on the creation of custom signing keys and JWT tokens to authenticate your users on your Realm App.


You will need to download the example project provided to create a signing key and JWT tokens that you are going to use later…

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