The Google Custom Search API enables licensed API access, via REST calls, to the Google search engine.
The Google Custom Search API exposes the Google search via a REST API. Invoking the service requires an API Key, and allows a fixed number of free calls before charges begin. It is a replacement/re-branding of the previous Google Search APIs which are deprecated as of 2010.
The API can handle requests in JSON or XML format.
Information on the API is available from Google: https://developers.google.com/custom-search/json-api/v1/overview