The microdata application programming interface (API) is a data service that allows software developers to access and use Census Bureau microdata within their applications. The service allows users to request results for individual microdata records or create custom statistics.

Like any data from the API, the microdata API is an efficient way to query data directly from Census Bureau servers with many advantages:

• No need to host data on own server
• Connects to statistical software like R and SAS
• Provides immediate access to most current data
• Facilitates building new mobile and Web applications
• Drives interactive data visualizations

Microdata Access on data.census.gov is a prime example of an interactive application powered by the microdata API. All the data in Microdata Access is being requested in real time from the microdata API and fed on your screen in a user-friendly way. This allows you to access the data by navigating an intuitive system rather than making requests directly to the microdata API, which is the focus of this guide. Please visit the Microdata Access Resources page if you would like to learn how to use Microdata Access on data.census.gov.

In comparison to bulk downloads of microdata from the file transfer protocol (FTP) sites, the microdata API and Microdata Access on data.census.gov provide unique benefits. They both allow you to:

• Create custom statistics without using your own statistical software.
• Download a subset of microdata records instead of the entire dataset. Specifically, you can limit your data requests to get data only for specific variables or geographies. You can also apply universe restrictions prior to downloading the microdata records.