Since search engine development requires building an index which is a tedious and space consuming process. Now-a-days all major search engines provide developers access to their resources through a set of APIs. In this paper we try to answer the following questions. What differences exist between search engines and their associated search APIs? Does search APIs really surrogate for the actual search engine within the research domain? If yes, then which APIs is more suitable? For our experiments, we have used the following search engines and their web search APIs: Yahoo, Google, MSN, and Naver. Our experimental results will help researchers to choose appropriate web search APIs that suit their requirements.