| ClosureLoader | ClosureLoader loads service definitions from a PHP closure. |
| FileLoader | FileLoader is the abstract class used by all built-in loaders that are file based. |
| IniFileLoader | IniFileLoader loads parameters from INI files. |
| PhpFileLoader | PhpFileLoader loads service definitions from a PHP file. |
| XmlFileLoader | XmlFileLoader loads XML files service definitions. |
| YamlFileLoader | YamlFileLoader loads YAML files service definitions. |