| APCBackend | Backend class using the Alternative PHP Cache |
| ArrayBackend | Backend class for testing using arrays for data storage |
| BackendSkeleton | The base class for all backends |
| FileBackend | Backend class using simple file-based storage |
| MemcacheBackend | Backend class using memcached |
| PCA | Implements a factory pattern to manage various backends |
| PDOBackend | Backend class using a database (mySQL; Postgres, ...) |
1.5.6