diff --git a/oauth2client/client.py b/oauth2client/client.py
new file mode 100644
index 0000000..761cbec
--- /dev/null
+++ b/oauth2client/client.py
@@ -0,0 +1,326 @@
+# Copyright 2010 Google Inc. All Rights Reserved.
+
+"""An OAuth 2.0 client
+
+Tools for interacting with OAuth 2.0 protected
+resources.
+"""
+
+__author__ = 'jcgregorio@google.com (Joe Gregorio)'
+
+import copy
+import datetime
+import httplib2
+import logging
+import urllib
+import urlparse
+
+try: # pragma: no cover
+  import simplejson
+except ImportError: # pragma: no cover
+  try:
+    # Try to import from django, should work on App Engine
+    from django.utils import simplejson
+  except ImportError:
+    # Should work for Python2.6 and higher.
+    import json as simplejson
+
+try:
+    from urlparse import parse_qsl
+except ImportError:
+    from cgi import parse_qsl
+
+
+class Error(Exception):
+  """Base error for this module."""
+  pass
+
+
+class RequestError(Error):
+  """Error occurred during request."""
+  pass
+
+
+class MissingParameter(Error):
+  pass
+
+
+def _abstract():
+  raise NotImplementedError('You need to override this function')
+
+
+class Credentials(object):
+  """Base class for all Credentials objects.
+
+  Subclasses must define an authorize() method
+  that applies the credentials to an HTTP transport.
+  """
+
+  def authorize(self, http):
+    """Take an httplib2.Http instance (or equivalent) and
+    authorizes it for the set of credentials, usually by
+    replacing http.request() with a method that adds in
+    the appropriate headers and then delegates to the original
+    Http.request() method.
+    """
+    _abstract()
+
+class Flow(object):
+  """Base class for all Flow objects."""
+  pass
+
+
+class OAuth2Credentials(Credentials):
+  """Credentials object for OAuth 2.0
+
+  Credentials can be applied to an httplib2.Http object
+  using the authorize() method, which then signs each
+  request from that object with the OAuth 2.0 access token.
+
+  OAuth2Credentials objects may be safely pickled and unpickled.
+  """
+
+  def __init__(self, access_token, client_id, client_secret, refresh_token,
+      token_expiry, token_uri, user_agent):
+    """Create an instance of OAuth2Credentials
+
+    This constructor is not usually called by the user, instead
+    OAuth2Credentials objects are instantiated by
+    the OAuth2WebServerFlow.
+
+    Args:
+      token_uri: string, URI of token endpoint
+      client_id: string, client identifier
+      client_secret: string, client secret
+      access_token: string, access token
+      token_expiry: datetime, when the access_token expires
+      refresh_token: string, refresh token
+      user_agent: string, The HTTP User-Agent to provide for this application.
+
+
+    Notes:
+      store: callable, a callable that when passed a Credential
+        will store the credential back to where it came from.
+        This is needed to store the latest access_token if it
+        has expired and been refreshed.
+    """
+    self.access_token = access_token
+    self.client_id = client_id
+    self.client_secret = client_secret
+    self.refresh_token = refresh_token
+    self.store = None
+    self.token_expiry = token_expiry
+    self.token_uri = token_uri
+    self.user_agent = user_agent
+
+  def set_store(self, store):
+    """Set the storage for the credential.
+
+    Args:
+      store: callable, a callable that when passed a Credential
+        will store the credential back to where it came from.
+        This is needed to store the latest access_token if it
+        has expired and been refreshed.
+    """
+    self.store = store
+
+  def __getstate__(self):
+    """Trim the state down to something that can be pickled.
+    """
+    d = copy.copy(self.__dict__)
+    del d['store']
+    return d
+
+  def __setstate__(self, state):
+    """Reconstitute the state of the object from being pickled.
+    """
+    self.__dict__.update(state)
+    self.store = None
+
+  def _refresh(self, http_request):
+    """Refresh the access_token using the refresh_token.
+
+    Args:
+       http: An instance of httplib2.Http.request
+           or something that acts like it.
+    """
+    body = urllib.urlencode({
+      'grant_type': 'refresh_token',
+      'client_id': self.client_id,
+      'client_secret': self.client_secret,
+      'refresh_token' : self.refresh_token
+      })
+    headers = {
+        'user-agent': self.user_agent,
+        'content-type': 'application/x-www-form-urlencoded'
+    }
+    resp, content = http_request(self.token_uri, method='POST', body=body, headers=headers)
+    if resp.status == 200:
+      # TODO(jcgregorio) Raise an error if loads fails?
+      d = simplejson.loads(content)
+      self.access_token = d['access_token']
+      self.refresh_token = d.get('refresh_token', self.refresh_token)
+      if 'expires_in' in d:
+        self.token_expiry = datetime.timedelta(seconds = int(d['expires_in'])) + datetime.datetime.now()
+      else:
+        self.token_expiry = None
+      if self.store is not None:
+        self.store(self)
+    else:
+      logging.error('Failed to retrieve access token: %s' % content)
+      raise RequestError('Invalid response %s.' % resp['status'])
+
+  def authorize(self, http):
+    """
+    Args:
+       http: An instance of httplib2.Http
+           or something that acts like it.
+
+    Returns:
+       A modified instance of http that was passed in.
+
+    Example:
+
+      h = httplib2.Http()
+      h = credentials.authorize(h)
+
+    You can't create a new OAuth
+    subclass of httplib2.Authenication because
+    it never gets passed the absolute URI, which is
+    needed for signing. So instead we have to overload
+    'request' with a closure that adds in the
+    Authorization header and then calls the original version
+    of 'request()'.
+    """
+    request_orig = http.request
+
+    # The closure that will replace 'httplib2.Http.request'.
+    def new_request(uri, method='GET', body=None, headers=None,
+                    redirections=httplib2.DEFAULT_MAX_REDIRECTS,
+                    connection_type=None):
+      """Modify the request headers to add the appropriate
+      Authorization header."""
+      if headers == None:
+        headers = {}
+      if ((self.token_expiry is not None) and (self.token_expiry <= datetime.datetime.now())):
+        logging.info("Refreshing because %s <= %s" %(self.token_expiry, datetime.datetime.now()))
+        self._refresh(request_orig)
+      headers['authorization'] = 'WRAP access_token=' + self.access_token
+      if 'user-agent' in headers:
+        headers['user-agent'] = self.user_agent + ' ' + headers['user-agent']
+      else:
+        headers['user-agent'] = self.user_agent
+      resp, content = request_orig(uri, method, body, headers,
+                          redirections, connection_type)
+      if resp.status == 401 and 'invalid_token' in resp.get('www-authenticate', ''):
+        logging.info("Refreshing because we got a 401")
+        self._refresh(request_orig)
+        return request_orig(uri, method, body, headers,
+                            redirections, connection_type)
+      else:
+        return (resp, content)
+
+    http.request = new_request
+    return http
+
+
+class OAuth2WebServerFlow(Flow):
+  """Does the Web Server Flow for OAuth 2.0.
+
+  OAuth2Credentials objects may be safely pickled and unpickled.
+  """
+
+  def __init__(self, client_id, client_secret, scope, user_agent,
+      authorization_uri='https://www.google.com/accounts/o8/oauth2/authorization',
+      token_uri='https://www.google.com/accounts/o8/oauth2/token',
+      **kwargs):
+    """Constructor for OAuth2WebServerFlow
+
+    Args:
+      client_id: string, client identifier
+      client_secret: string client secret
+      scope: string, scope of the credentials being requested
+      user_agent: string, HTTP User-Agent to provide for this application.
+      authorization_uri: string, URI for authorization endpoint
+      token_uri: string, URI for token endpoint
+      **kwargs: dict, The keyword arguments are all optional and required
+                        parameters for the OAuth calls.
+    """
+    self.client_id = client_id
+    self.client_secret = client_secret
+    self.scope = scope
+    self.user_agent = user_agent
+    self.authorization_uri = authorization_uri
+    self.token_uri = token_uri
+    self.params = kwargs
+    self.redirect_uri = None
+
+  def step1_get_authorize_url(self, redirect_uri='oob'):
+    """Returns a URI to redirect to the provider.
+
+    Args:
+      redirect_uri: string, Either the string 'oob' for a non-web-based
+                    application, or a URI that handles the callback from
+                    the authorization server.
+
+    If redirect_uri is 'oob' then pass in the
+    generated verification code to step2_exchange,
+    otherwise pass in the query parameters received
+    at the callback uri to step2_exchange.
+    """
+
+    self.redirect_uri = redirect_uri
+    query = {
+      'response_type': 'code',
+      'client_id': self.client_id,
+      'redirect_uri': redirect_uri,
+      'scope': self.scope,
+      }
+    query.update(self.params)
+    parts = list(urlparse.urlparse(self.authorization_uri))
+    query.update(dict(parse_qsl(parts[4]))) # 4 is the index of the query part
+    parts[4] = urllib.urlencode(query)
+    return urlparse.urlunparse(parts)
+
+  def step2_exchange(self, code):
+    """Exhanges a code for OAuth2Credentials.
+
+    Args:
+      code: string or dict, either the code as a string, or a dictionary
+        of the query parameters to the redirect_uri, which contains
+        the code.
+    """
+
+    if not (isinstance(code, str) or isinstance(code, unicode)):
+      code = code['code']
+
+    body = urllib.urlencode({
+      'grant_type': 'authorization_code',
+      'client_id': self.client_id,
+      'client_secret': self.client_secret,
+      'code': code,
+      'redirect_uri': self.redirect_uri,
+      'scope': self.scope
+      })
+    headers = {
+        'user-agent': self.user_agent,
+        'content-type': 'application/x-www-form-urlencoded'
+    }
+    h = httplib2.Http()
+    resp, content = h.request(self.token_uri, method='POST', body=body, headers=headers)
+    if resp.status == 200:
+      # TODO(jcgregorio) Raise an error if simplejson.loads fails?
+      d = simplejson.loads(content)
+      access_token = d['access_token']
+      refresh_token = d.get('refresh_token', None)
+      token_expiry = None
+      if 'expires_in' in d:
+        token_expiry = datetime.datetime.now() + datetime.timedelta(seconds = int(d['expires_in']))
+
+      logging.info('Successfully retrieved access token: %s' % content)
+      return OAuth2Credentials(access_token, self.client_id, self.client_secret,
+          refresh_token, token_expiry, self.token_uri,
+          self.user_agent)
+    else:
+      logging.error('Failed to retrieve access token: %s' % content)
+      raise RequestError('Invalid response %s.' % resp['status'])