Hamsterdb is written in ANSI C and supports a B+Tree index structure, uses memory mapped I/O (if available), supports cursors, and can create in-memory databases.

ChurchInfo is a php/mySQL database to keep track of people, families, groups, pledges and payments, Sunday school classes, etc.

Free and open source version of Java database Daffodil DB. Available in both network and embedded editions.

News, information, and tools related to open source database platforms.

Provides small footprint, high performance, and easy-to-use embedded database solutions. Also sells technical support and consulting.

picoSQL is a SQL-based, multi-user, client/server RDBMS, derived from a commercial project [GPL].

Both a single user and client/server versions with ODBC drivers. Distributed under a modified GPL that allows distribution of applications without including source code. Commercial support available.

An Object-Oriented Database and Web Services (SDK) written in Java, includes documentation, example code and information about the author.

Java library to execute SQL statements stored in external library files. This separation increases readability, eases maintenance, and allows separate testing and documentation. [MIT]

Database server written in Ruby that supports tables, indexes, triggers, sequences, views, stored procedures, and transactions.