When you set up nOps in your AWS account, the following CloudFormation stack is created: https://s3-us-west-2.amazonaws.com/nops-users/nOpsRole.yaml.

This stack creates a cross-account role that allows the nOps service to get access to your resources. The S3 bucket you created for nOps is used for log data that populates the nOps reports when you log in to your account at https://www.nops.io.

nOps queries your resources to produce reports that are similar to the functionality of AWS Trusted Advisor, and also automates answers to many of the questions that come up during a Well-Architected review. It is common for nOps users to quickly find significant cost-saving opportunities within their accounts, and also find places in their architecture where they are not following best practices.