The CDB File Type
CDB Icon used by CastleDB
CastleDB (http://castledb.org/)
CastleDB is a light weight database written in Haxe with data composed of sheets. It makes storing structured data extremely simple, much like working with an Excel spreadsheet and much simpler than a traditional database. The resulting data is stored in JSON making it easily used in almost any game engine or programming language. Most interestingly you can treat 2D game levels just like any other data using the built-in level editor. - GameFromScratch
Currently, there is one file using this extension, which is data.cdb.
This file serves as a configuration file for most of the game's content, ranging from the pixels scale, to map tile chunks for the procedural generation.
PS: If you use CellPacker for unpacking, it will also create a data.exported.cdb file, which is not a file that's originally in the game, it's probably there just as a backup.
The image above shows CastleDB being used to edit map tile's properties. (Courtesy of Gamasutra)
CastleDB can also be used to create level tile chunks using it's built-in tilemap editor. (Courtesy of Gamasutra)
CDB files can be edited with CastleDB or edited directly as JSON.