The Google+ API is the programming interface to Google+. You can use the API to integrate your app or website with Google+. This enables users to connect with each other for maximum engagement using Google+ features from within your application. The Google+ API currently provides read-only access to public data. Applications are limited to a courtesy usage quota. This should provide enough access for you to preview the API and to start thinking about how you want to build your application.
When you use the Google APIs Client Libraries, you benefit from better language integration, improved security, and support for making authenticated calls.
In the table below, the first column shows each library's stage of development; note that some are still in early stages. The second column links to the main page for each library.
|Client Library||Project Home||Starter Project|
|Google APIs Client Library for .NET (beta)||google-api-dotnet-client||-|
|Google APIs Client Library for Google Web Toolkit (alpha)||gwt-google-apis||-|
|Google APIs Client Library for Java (beta)||google-api-java-client||google-plus-java-starter|
|Google APIs Client Library for Objective C (alpha)||google-api-objectivec-client||-|
|Google APIs Client Library for PHP (beta)||google-api-php-client||google-plus-php-starter|
|Google APIs Client Library for Python (beta)||google-api-python-client||google-plus-python-starter|
|Google APIs Client Library for Ruby (alpha)||google-api-ruby-client||google-plus-ruby-starter|