AWS Public IP Address Ranges Now Available in JSON Form

Amazon Web Services (AWS) publishes its current IP address ranges in JSON format. 

To view the current ranges, download the .json file. To maintain history, save successive versions of the  .json file on your system. To determine whether there have been changes since the last time that you saved the file, check the publication time in the current file and compare it to the publication time in the last file that you saved.

Reference:

1. http://aws.amazon.com/blogs/aws/aws-ip-ranges-json/