Q: Google Calendar and C# I have to create a windows app to sync some data (such as events and user data) from my sql server database to google calendar in the background without prompting users for login credentials. The calendar application has to be able to work offline on schedule with no internet connectivity. I know there are already some commercial applications out there but i want to do it with google api. Could you point me in the right direction? Thanks. A: Using OAuth 2.0 you can create a service account for your application. You then need to register that service account as an "application" in the Calendar API dashboard, and get the client ID and client secret. You then build an authenticated http request with those credentials and the required scopes, and you should be good to go. This is a very common scenario, and the code you write will handle authenticating and accessing data on behalf of the user. A: It's a bit late, but I did not manage to see it anywhere else, so here it goes: This may sound silly, but I would never do such kind of access to the calendars of other people. I've tried doing it and it takes a very long time to get the access and it requires asking the user for a lot of information. Best solution I came up with is using the google API to insert events into a personal calendar, and access this personal calendar from another personal calendar using Google Dekstop Sharing. However, if your application has only one user, you could use Calendar Data API to directly insert an event into any calendar you want, and simply access this calendar using a calendar ID. You will need to register the application with a redirect URI to handle redirecting the user back to your page after granting the authorization for your app. Good luck and happy coding. A: Check this documentation : Google Calendar API with Service Accounts This Python Google App Engine code is an example of how to use Google Calendar API with OAuth 2.0 and authorization by using service accounts. Also check this part of the documentation : Accessing Calendars using Service Accounts This part of the documentation illustrates how to use Google Calendar API v3 with service accounts and authorization, along with the Google API Python client library. You can download Google API for Python here. Example : from __future__ import print_function from googleapiclient.discovery import build from google_auth_oauthlib.flow import InstalledAppFlow from google.auth.transport.requests import Request from google.auth.transport.requests import AuthorizedSession from oauth2client.service_account import ServiceAccountCredentials # [START import_service_account] # Get the credentials ready credentials = ServiceAccountCredentials.from_json_keyfile_name('client_secrets.json') # Request the token flow = InstalledAppFlow.from_client_secrets_file('client_secrets.json', SCOPES) credentials = flow.run_local_server(port=0) # Check that the token is in fact valid. print('Checking for token in %s' % credentials.token_expiry) session = AuthorizedSession(credentials=credentials) req = session.request(service_name='plus', version='v1') print(req) response = req.execute() # Check response in dict format print(response) # [END import_service_account] def create_event(title, desc, location): """Create an Event.""" event = { 'created': '2011-06-19T19:18:48.748Z', 'title': title, 'description': desc, 'summary': 'Bike trip to Philly', 'location': location, 'dates': { 'start': '2011-06-19', 'end': '2011-06-19' } } return event # [START insert_event] event = create_event('Penny Farthing', 'Cycled to work in London.', 'London, United Kingdom') service = build('calendar', 'v3', developerKey=credentials.token_uri) event = service.events().insert(calendarId='primary', body=event).execute() # [END insert_event] print(event.get('htmlLink')) #https://www.google.com/calendar/event?eid=XqEi1_aYBvDkF9nEe-3zfqVgU%3Af0g%3A0N0Lq6y2r5Wfkz6lLb8OyhW5J4k&ctz=Europe%2FLondon&src=gbq0%2Frsrc%2Fvq3.