BacketDB is database that provide powerfull mechanism to manage collections of objects. It is accessiable through REST api. Test example is run at Heroku.
Some examples you could find at tests
GET / - returns list of backet ids.
GET /:id - returns full backet object.
GET /:id/aggregates - returns aggregated values for requested backet.
POST / - create new backet.
POST /:id/item - add item to backet.
DELETE /:id - remove backet.