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 🇺🇸