S3 isn't a server, it's an object store. This uses Lambda (the serverless part) to fetch source data on demand, combine, reproject to web mercator, and send to

S3 isn't a server, it's an object store. This uses Lambda (the serverless part) to fetch source data on demand, combine, reproject to web mercator, and send to the client. There are varied definitions of serverless; it isn't "as serverless" as the browser loading data directly from S3, but an AWS marketing person would call this usage of Lambda serverless.