Transposit can create simple APIs. In this sample app, Transposit exposes a list of all AWS regions to which you have access (and that have the EC2 service running in them).
You need a free Transposit account and an AWS account. The AWS user needs to have programmatic access (you need an
aws_access_key_id and a
aws_regionswebhook, something like
Consider upgrading this to show the list of availability zones as well as regions.