AWS CloudFormation Supports YAML in CloudFormation Designer

You can now create and edit AWS CloudFormation templates in CloudFormation Designer using YAML. CloudFormation Designer allows you to create and modify CloudFormation templates using a drag-and-drop interface which automatically updates the underlying template. Previously, you could only create or edit your CloudFormation templates in JSON. Now, you can create and edit templates in both JSON and YAML using the integrated editor. You can also convert JSON templates to YAML and vice-versa. Visit here to learn more.
Quelle: aws.amazon.com