Buckets uses MongoDB as it’s database.
On Mac OS X, you can quickly install with:
brew install mongodb
If you want to start MongoDB automatically with your Mac, you include an easy LaunchAgent:
ln -sfv /usr/local/opt/mongodb/*.plist ~/Library/LaunchAgents launchctl load ~/Library/LaunchAgents/homebrew.mxcl.mongodb.plist
For Windows/Linux users, please just refer to MongoDB homepage and follow the installation instructions.