They use Savings Plans, Reserved Instances, Group Buying and negiotiation to save 60% on AWS Hosting fees
They add you to their billing organisation and it's a free service, they keep a small percentage of the savings
"We only take permissions to enroll you into group buying & claim discounts
We cannot start, stop or change an instance
We cannot access your code, or your user data"
Works for these services:
EC2
Sagemaker
Redshift
EC2 Data Transfer
ECS
Lambda
EBS
Elastic Cache
Opensearch
S3
Medialive
Would they have access to your resources and be able to turn on/off at their will if need be?