SQLite

http://www.sqlite.org/ - SQLite is a software library that implements a self-contained, serverless, zero-configuration, transactional SQL database engine

H2

http://www.h2database.com/html/main.html - The Java SQL database

Cobar

https://github.com/alibaba/cobar - 阿里巴巴分布式数据库中间件

Druid

https://github.com/alibaba/druid - 为监控而生的数据库连接池

Otter

https://github.com/alibaba/otter - 阿里巴巴分布式数据库同步系统