Which AWS service has unlimited free use?

Explanations:

Amazon SageMaker offers a free tier, but it is not unlimited. After the free tier usage is exhausted, charges apply based on usage.

AWS Config has a free tier with limited usage, but it is not unlimited. Charges apply when the free tier limits are exceeded.

AWS Organizations is free to use for organizing and managing AWS accounts. There are no additional charges unless other AWS services are used within the organization.

Amazon CloudWatch offers a free tier with limited metrics, logs, and alarms, but it is not unlimited. Charges apply once the free tier usage limits are exceeded.