App Engine Services Summary
Datastore: The Datastore is a schemaless object datastore, with a query engine and atomic transactions.
Blobstore API: The Blobstore API allows your app to serve data objects, called blobs, that are much larger than the size allowed for objects in the Datastore service.
Capabilities API: With the Capabilities API, your application can detect outages and scheduled downtime for specific API capabilities.
Images API: The Images API can resize, rotate, flip, and crop images. It can also enhance photographs using a predefined algorithm.
Mail API: The Mail API sends email messages on behalf of the app's administrators, and on behalf of users with Google Accounts. Apps can receive email at various addresses.
Memcache: Memcache is a distributed in-memory data cache to be used in front of or in place of robust persistent storage for some tasks.
Namespace: The Namespaces feature allows you to implement multitenancy in your applications.
OAuth: OAuth is a protocol that allows a user to grant a third party limited permission to access a web application on her behalf, without sharing her credentials (username and password) with the third party.
Task Queue API: The Task Queue API allows applications to perform work initiated by a user request, outside of that request.
URL Fetch API: The URL Fetch API allows applications to fetch resources and communicate with other hosts over the Internet using HTTP and HTTPS requests.
Users API: The Users API allows applications to authenticate users who have Google Accounts or accounts on your own Google Apps domain.
XMPP API: The XMPP API allows applications to send and receive instant messages to and from users of XMPP-compatible instant message services.