It's the SQLite driver for JDBC. We decided that the MVP would be to get Zipkin running on SQLite, so until we can load config dynamically I just put this in directly. But Anorm supports any SQL database in theory, and the DB class already has settings for MySQL, PostgreSQL, and H2 -- so one of the TODOs is to figure out the easiest way for people who want to use something other than SQLite to get the right driver dependencies loaded.