| FirebaseApp | The entry point of Firebase SDKs. |
| FirebaseOptions | Configurable Firebase options. |
| FirebaseOptions.Builder | Builder for constructing FirebaseOptions. |
| IncomingHttpResponse | Contains information that describes an HTTP response received by the SDK. |
| OutgoingHttpRequest | Contains the information that describe an HTTP request made by the SDK. |
| ThreadManager | An interface that controls the thread pools and thread factories used by the Admin SDK. |
| ErrorCode | Platform-wide error codes that can be raised by Admin SDK APIs. |
| FirebaseException | Base class for all Firebase exceptions. |