CalDAV is an extension of WebDAV that provides a standard for clients to access calendar information on a remote server.
Google provides a CalDAV interface that you can use to view and manage calendars using the CalDAV protocol.
Specifications
For each of the relevant specifications, Google's CalDAV support is as follows:
- rfc4918: HTTP Extensions for Web Distributed Authoring and Versioning
(WebDAV)
- Supports the HTTP methods
GET
,PUT
,HEAD
,DELETE
,POST
,OPTIONS
,PROPFIND
andPROPPATCH
. - Does not support the HTTP methods
LOCK
,UNLOCK
,COPY
,MOVE
, orMKCOL
, or theIf*
header (except forIf-Match
). - Does not support arbitrary (user-defined) WebDAV properties.
- Does not support WebDAV Access Control (rfc3744).
- Supports the HTTP methods
- rfc4791: Calendaring Extensions to WebDAV (CalDAV)
- Supports the HTTP method
REPORT
. All reports except free-busy-query are implemented. - Does not support the HTTP method
MKCALENDAR
. - Does not support the
AUDIO
action.
- Supports the HTTP method
- rfc5545: iCalendar
- Data exposed in the CalDAV interface is formatted according to the iCalendar specification.
- Does not currently support
VTODO
orVJOURNAL
data. - Does not support the Apple iCal® extension to allow user-settable URL properties.
- rfc6578: Collection Synchronization for WebDAV
- Client applications must switch to this mode of operation after the initial sync.
- rfc6638: Scheduling Extensions to CalDAV
- Supports a trivial "inbox," which is always empty.
- Invitations you receive are automatically delivered into your "events" collection rather than being placed into your "inbox."
- Does not support free-busy lookup.
- caldav-ctag-02: Calendar Collection Entity Tag (CTag) in CalDAV
- The calendar
ctag
is like a resourceetag
; it changes when anything in the calendar has changed. This allows the client application to quickly determine that it does not need to synchronize any changed events.
- The calendar
- calendar-proxy: Calendar User Proxy Functionality in CalDAV
- To improve the performance of calendar synching from iOS devices, which
don't support delegation, using the
calendar-proxy-read-for
orcalendar-proxy-write-for
properties with an iOS UserAgent will fail.
- To improve the performance of calendar synching from iOS devices, which
don't support delegation, using the
We have not yet provided a full implementation of all of the relevant specifications. However, for many clients such as Apple's Calendar app the CalDAV protocol should interoperate correctly.
Note: For account security and to prevent abuse, Google might set cookies on client applications that access data via CalDAV.
Creating your client ID
To use the CalDAV API you need to have a Google Account. If you already have an account you can use, then you're all set.
Before you can send requests to the CalDAV API, you must register your client with the Google API Console by creating a project.
Go to the Google API Console. Click Create project, enter a name, and click Create.
The next step is to activate CalDAV API.To enable an API for your project, do the following:
- Open the API Library in the Google API Console. If prompted, select a project or create a new one. The API Library lists all available APIs, grouped by product family and popularity.
- If the API you want to enable isn't visible in the list, use search to find it.
- Select the API you want to enable, then click the Enable button.
- If prompted, enable billing.
- If prompted, accept the API's Terms of Service.
To find your project's client ID and client secret, do the following:
- Select an existing OAuth 2.0 credential or open the Credentials page.
- If you haven't done so already, create your project's OAuth 2.0 credentials by clicking Create credentials > OAuth client ID, and providing the information needed to create the credentials.
- Look for the Client ID in the OAuth 2.0 client IDs section. For details, click the client ID.
Connecting to Google's CalDAV server
To use the CalDAV interface, a client program initially connects with the
calendar server at one of two starting points. In either case, the connection
must be made over HTTPS and must use the OAuth 2.0
authentication scheme. The CalDAV server will refuse to authenticate a request
unless it arrives over HTTPS with OAuth 2.0 authentication of a Google account.
Attempting to connect over HTTP or using Basic Authentication results in an HTTP
401 Unauthorized
status code.
If the client program (such as Apple's Calendar app) requires a principal collection as the starting point, the URI to connect to is:
https://apidata.googleusercontent.com/caldav/v2/calid/user
Where calid
should be replaced by the
"calendar ID" of the calendar to be accessed. This can be found through the
Google Calendar web interface as follows: in the pull-down menu next to the
calendar name, select Calendar Settings. On the resulting page
the calendar ID is shown in a section labeled Calendar
Address. The calendar ID for a user's primary calendar is the same as
that user's email address.
If a client program (such as Mozilla Sunbird) requires a calendar collection as the starting point, the URI to connect to is:
https://apidata.googleusercontent.com/caldav/v2/calid/events
The old endpoint https://www.google.com/calendar/dav is deprecated and no longer supported; use it at your own risk. We recommend you transition to the new endpoint format described above.
iCal® is a trademark of Apple Inc.