Starcounter is described as 'The Starcounter database is built with the real-time systems of today in mind. Real-time systems supporting thousands or millions of simultaneous users. Systems like online stores, location-based services or banking applications' and is an app in the Development category. There are more than 50 alternatives to Starcounter for a variety of platforms, including Linux, Windows, Mac, Online / Web-based and BSD. The best alternative is DBeaver, which is both free and Open Source. Other great apps like Starcounter are PostgreSQL (Free, Open Source), SQLite (Free, Open Source), MySQL Community Edition (Free, Open Source) and MongoDB (Free).
Firebird is a relational database offering many ANSI SQL-92 features that runs on Linux, Windows, and a variety of Unix platforms. Firebird offers excellent concurrency, high performance, and powerful language support for stored procedures and triggers.
RethinkDB pushes JSON to your apps in realtime. When your app polls for data, it becomes slow, unscalable, and cumbersome to maintain. RethinkDB is the open-source, scalable database that makes building realtime apps dramatically easier.
Cockroach is a distributed key/value datastore which supports ACID transactional semantics and versioned values as first-class features. The primary design goal is global consistency and survivability, hence the name.
HSQLDB (Hyper Structured Query Language Database) is a relational database management system written in Java. It has a JDBC driver and supports a large subset of SQL-92 and SQL:2008 standards. It offers a fast, small (around 1300 kilobytes in version 2.
DB2 offers industry leading performance, scale, and reliability on your choice of platform from Linux to z/OS. DB2 supports storing XML and relational data and offers SQL PL and PL/SQL procedural languages.
CUBRID is a comprehensive GPL/BSD open source relational database management system highly optimized for Web Applications. CUBRID is being developed in C/C++. Includes native HA, online hot backup, and other features. JDBC, PHP, ODBC/.NET, Ruby & Python APIs.