ObjectBox is described as 'DB is an easy & fast object-oriented mobile database for Android, Linux, soon iOS. It supports relations, JavaRx, Kotlin. It is 10X faster than SQLite. And POJOs are POJOs' and is an app in the Development category. There are four alternatives to ObjectBox for a variety of platforms, including Mac, Windows, Linux, iPhone and Android. The best alternative is SQLite, which is both free and Open Source. Other great apps like ObjectBox are Realm (Free, Open Source), Matisse (Paid) and LMDB (Free, Open Source).
SQLite is a software library that implements a self-contained, serverless, zero-configuration, transactional SQL database engine. SQLite is the most widely deployed SQL database engine in the world. The source code for SQLite is in the public domain.
Realm enables any development team, no matter the size, to include difficult-to-build features like two-way data sync and realtime collaboration. Devote more time to what makes your app truly unique and less time to maintaining services.