Realm vs RxDB
Realm
realm.github.io
RxDB
rxdb.infoSide by side
| Figure | Realm | RxDB |
|---|---|---|
| Price from | Free | $99/mo |
| Free plan | Yes | Yes |
| Free trial | — | — |
| Open source | — | — |
| Web | — | Yes |
| Windows | Yes | Yes |
| macOS | Yes | Yes |
| Linux | Yes | Yes |
| iOS | Yes | Yes |
| Android | Yes | Yes |
| API | — | Yes |
| Self-hosted | Yes | Yes |
| Plans published | 1 | 4 |
| Spec score · Mobile Databases | 7.7 (#18) | 8.1 (#9) |
| License | MongoDB said it would offer the renamed Atlas Device SDKs as a free open-source project under Apache License 2.0. | The free tier is under the Apache 2.0 license. |
| Product | Realm is an object database designed to run directly on phones, tablets, and wearables. | RxDB is a NoSQL database for JavaScript that runs directly in an app. |
| Support | The Realm documentation directs users to its forums, Stack Overflow, and GitHub issues for help. | Free users receive community support through GitHub and Discord, while Enterprise includes a support SLA with a 24-hour first response. |
Plans
In their own words
Realm
Realm is an object database for local data persistence in mobile and edge applications. It runs directly on phones, tablets, and wearables, and presents data as objects that developers can query in code without an ORM. The database supports relationships, generics, and vectorization. Its documentation describes apps continuing to work through weak signal, offline periods, or outages. Listed SDKs include Java, Swift, Objective-C, JavaScript, and .NET; the JavaScript implementation supports React Native on iOS and Android, as well as Node.js and Electron on Windows, macOS, and Linux. Realm Swift supports encryption in transit and at rest. Realm Studio can open and edit local and synced Realms and administer Realm Object Server instances. Former Device Sync connected data across users, devices, and a backend in real time, but MongoDB announced deprecation of Device Sync and Realm SDKs in September 2024. Realm is free and open source under Apache License 2.0.
RxDB
RxDB is a NoSQL database for JavaScript that runs inside an application and keeps data locally on the client. It supports offline operation, including applications that run entirely without a backend. When synchronization is needed, its Sync Engine connects to backends including RxServer, GraphQL, Firebase, Supabase, MongoDB, NATS, HTTP, CouchDB, WebRTC, Appwrite, Google Drive, and Microsoft OneDrive. Observable queries update as stored data changes. RxDB runs in browsers, mobile apps, desktop applications, and servers, with storage options including LocalStorage, IndexedDB, OPFS, SQLite, Node.js Filesystem, Expo Filesystem, MongoDB, and FoundationDB, among others. Collections use JSON Schema with validation and migration support. An encryption plugin protects locally stored documents with a password in browsers, React Native, and Node.js. The free tier is under Apache 2.0 and allows up to 13 open collections in parallel. Free users get community support through GitHub and Discord; Enterprise includes an SLA with a 24-hour first response. Pro costs $99 a month billed annually, and Pro Plus costs $239 a month billed annually.