Just speculating, because it's using a suite of AWS managed services throughout (CloudFront, S3, Route53, API Gateway) and it's a common design to use Lambda fu

Just speculating, because it's using a suite of AWS managed services throughout (CloudFront, S3, Route53, API Gateway) and it's a common design to use Lambda functions with API Gateway. Knowing that this is a very high profile, high traffic site launch, and knowing something of the attitudes of the USDS team, they are likely to want to minimize the number of moving parts and services they have to manage themselves. Also, observing the interaction of the site, which all boils down to a simple HTTP POST of a small JSON blob to the API Gateway endpoint, I am (again just speculating) assuming they are wanting to do minimal processing and just stuff the JSON into a database as quickly as possible. It could be an RDS database, but that still seems like too much administration, and especially since DynamoDB can do highly scalable writes, it just seems like the least surprising choice. I could be wrong, and it would be great to hear the team share on record what's actually under the hood, but given what we can confirm externally by observation plus what we know about the mission and the team, I feel reasonably confident it is all managed services, at least on the frontend component we can interact with.