Auditaz and AWS Compute Optimizer
Compute Optimizer recommends the right size for compute. Cost waste is a great deal more than instance size.
What each one does
Compute Optimizer applies machine learning to CloudWatch metrics to recommend sizing for EC2, Auto Scaling groups, EBS volumes, Lambda functions and some RDS types. At what it does it is good, it is free, and it is AWS's own.
But sizing is one category of waste among many. An unattached volume, a snapshot past its retention, an idle Elastic IP, a bucket with no lifecycle rule, an empty hosted zone, NAT traffic a VPC endpoint would absorb, a Savings Plan coverage gap — none of those is a question of instance size, and none of them shows up there.
Side by side
| Compute Optimizer | Auditaz | |
|---|---|---|
| Scope | Compute and EBS sizing | 31 checks across 10 services |
| Recoverable amount | Estimated per sizing recommendation | Account total, without counting the same saving twice |
| Leftover resources | Out of scope | Orphaned, idle and forgotten, per region |
| Reservations and Savings Plans | Out of scope | Coverage gap, as a decision to make |
When the other tool is the right call
For the specific question "is this instance the right size", Compute Optimizer has more history and more signal than we do, and it is free. Use both: it for fine-grained sizing, us for everything left over outside compute.