Google offically annouunce that Web Search API retires on August 29, 2014, which recommends the developers to use the customuzied search API in the place where the previous API used.
As said by Google devleopers:
“On November 1, 2010, we announced the deprecation of the Web Search API. As our policy at the time, we supported the API for a three year period (and beyond), but as all things come to an end, so has its deprecation window.”
- Google Developers Blog
Google reviewing the Customer search API considers 100 free quota on queries per day.