Packages 
Package Description
com.google.appengine.api
Provides facilities for server lifecycle management, threading and namespaces/multitenancy.
com.google.appengine.api.appidentity
Provides a service to sign arbitrary byte arrays using an internally-generated, rotated private key.
com.google.appengine.api.backends
Provides access to long-running, addressable servers.
com.google.appengine.api.blobstore
Provides management and persistent storage of large, immutable byte arrays.
com.google.appengine.api.capabilities
Provides status information about the services available via the GAE APIs.
com.google.appengine.api.datastore
Provides persistent storage, also accessible via JDO or JPA interfaces.
com.google.appengine.api.images
Provides facilities for the creation and manipulation of images.
com.google.appengine.api.internal  
com.google.appengine.api.log
Provides access to request logs and application logs.
com.google.appengine.api.mail
Provides a service to send email messages on behalf of administrators or authenticated users, also accessible via a JavaMail interface.
com.google.appengine.api.mail.stdimpl  
com.google.appengine.api.memcache
Provides fast but unreliable data storage, also accessible via a JCache interface.
com.google.appengine.api.modules
Utility functions for working with App Engine services (previously known as modules).
com.google.appengine.api.oauth
Provides a method for clients to access server resources on behalf of a resource owner, as well as a process for end-users to authorize third-party access to their server resources without sharing their credentials.
com.google.appengine.api.quota
Provides measurement of API and CPU usage during requests.
com.google.appengine.api.search
Provides a service for indexing documents and retrieving them using search queries.
com.google.appengine.api.search.checkers  
com.google.appengine.api.search.query  
com.google.appengine.api.taskqueue
Provides a mechanism to perform work initiated by a user request, outside of that request.
com.google.appengine.api.urlfetch
Provides a service to make HTTP/S requests of other servers on the internet.
com.google.appengine.api.users
Provides facilities to check if a user has authenticated, retrieve their email address, and check if they are an administrator for this application.
com.google.appengine.api.utils
Provides common utility classes.
com.google.appengine.spi
Support for alternate implementations of Google App Engine services.
com.google.appengine.tools.compilation  
com.google.apphosting.api  
com.google.apphosting.utils.remoteapi
The com.google.apphosting.utils.remoteapi package contains a servlet that implements the server portion of Google App Engine's Remote API functionality, which allows client code to execute arbitray API calls on a remote App Engine application.
com.google.apphosting.utils.security.urlfetch  
com.google.apphosting.utils.servlet  
com.google.storage.onestore