How do I start?
There are two sets of libraries available for the Authentication service. Choose the one that suits your needs:
Authentication for Installed Applications: The ClientLogin API lets you incorporate programmatic login into your desktop or mobile applications. This API supports CAPTCHA for greater security against password trollers.
Authentication for Web Applications: These APIs let your web application access a user's Google data without handling the user's login information. Google provides a library based on the OAuth open standard. As an alternative, developers can continue to use Google's AuthSub library, which offers several options related to security requirements.
* CAPTCHA is a trademark of Carnegie Mellon University
What is the Account Authentication Service?
At Google, we welcome the development of third-party applications that communicate and exchange information with Google services for their users. Many Google services are protected by Google accounts, and users must explicitly authorize third-party access to their accounts. This means your application needs some way to manage user authorization. The Google Accounts Authentication Service helps simplify this task by validating requests for access and issuing authentication tokens. Many Google services support the Authentication Service, including those based on the Google Data API.
Our goal in providing this service is to enhance both performance and security, as well as to streamline the authentication process for application developers.
The Authentication Service can be used to access both regular Google accounts and hosted Google accounts (Google Apps). Although the user experience varies slightly, the process of managing authentication programmatically is the same for both types of accounts; no special steps need to be taken.