AWS Lambda Web Functions run your web application as a standard HTTP server. Your code listens on a port and handles requests directly, so you can use Node.js frameworks such as Express, Hono, or React Router with no Lambda-specific adapter layers. You develop and test locally like any other Node.js app.

Deploy a .zip file and Lambda creates an HTTPS endpoint, manages the execution environments, and scales with traffic, including to zero. Each environment serves many concurrent requests, so fewer environments handle more traffic. You can also deploy across multiple AWS Regions behind a single endpoint, with each request routed to the nearest Region.

You pay for requests, active CPU time, memory over the life of each execution environment, and data transfer. A request that waits on a database query or an external API call uses little CPU while it waits, which keeps costs low for I/O-heavy web apps and APIs.