https://vk.com/dev

Open API is a system for developers of third party sites which enables easy authorization of VK users on your site. Also, if users agree, you can get access to information about their friends, photos, audios, videos and other VK data for deeper integration with your project.

As part of connection to Open API, a special application is created which allows to use all current VK API methods on your site. In addition, Open API can simplify registration of new users on your site if they already have a VK account.

For the user authorization Open API uses VK.Auth object methods:
3.1. VK.Auth.login
Parameters: callback (function), settings (integer)

Opens a pop-up window for user authorization with its VK account. If user is already authorized in VK but did not install the application, a permission for access to personal data is requested. If user is authorized in VK and installed the application to his/her page, the pop-up window is closed immediately and user session data are returned in a callback. If settings parameter is set, user settings of the application are compared to the value passed in settings, and if needed, missing settings are requested. For the current list of settings bit masks go to the page with access permissions.

Since this function calls a pop-up window, then to avoid pop-up window blocking it shall be called in the user event handler (e.g. clicking the object with the mouse button).

This method generates auth.login event.

here can be maximum 3 requests to API methods per second from a client.

Maximum amount of server requests depends on the app’s users amount.
If an app has less than 10 000 users, 5 requests per second, up to 100 000 – 8 requests, up to 1 000 000 – 20 requests, 1 000 000+ – 35 requests.

If one of this limits is exceeded, the server will return following error: ‘Too many requests per second’.

If your app’s logic implies many requests in a row, check the execute method.

Except the frequency limits there are quantitative limits on calling the methods of the same type. By obvious reasons we don’t provide the exact limits info.

On excess of a quantitative limit access to a particular method will require captcha (see captcha_error). After that it may be temporarily limited (in this case the server doesn’t answer on particular method’s requests but easily processes any other requests).