I have two dataset. One with FIPS code and second with Longitude and Latitude. I have to combine this sets. What is the good idea to do ? convertion FIPS to Latitude and Longitude? Is there dataset or API available for this?

[#1]

Have you checked out, below gist gives an example of how to call the API, you can use nifi to enrich the data periodically before you join.

https://gist.github.com/ramhiser/f09a71d96a4dec80994c

[#2]

@Sonu Sonu

You can use FCC Conversion API to get fips code from lat & long

For example: http://data.fcc.gov/api/block/2010/find?latitude=40.0&longitude=-85

Also,

Please check out http://www.datasciencetoolkit.org/ a ready to use virtual machine(VM) for geocoding and reverse geocoding, it provides useful information including FIPS codes.

i hope it will help.