Data API is the primary ways which is used for published data on the Internet. It is important to understand when Data API is the right technology for a particular database or service. This is refers to putting all of the data into a file or a set of files so that all of the data can be acquired with a few simple downloads. A Data API or read-only API is a method for providing small slices of the data. There are certain datasets that are so large in the information scenes such as the Census data about every ZIP code and the volatile such as stock market prices that change in microseconds which are downloading by the Data API. The ability for a software developer to query for a small part of these databases can lower the barrier to entry and make it easier for developers to begin using the data. Data APIs provide only a small window into the data, Means that while bulk data can be used to build any application and a Data API can only be used to build applications that require a small amount of the data at a time.