AWS Lambda Web Functions run an ordinary HTTP server and bill for active CPU, not waiting

Serguey Asael Shinder13 October 2026, 06:542 min read

AWS has announced Lambda Web Functions, which it calls a new serverless compute primitive in which the function's code handles HTTP requests directly. Instead of implementing a Lambda handler, the code listens on a port and serves requests as it would on any HTTP server, so frameworks such as Express or Hono run without adapters or custom configuration.

Billing model. AWS says customers pay for active CPU time and the memory the environment holds, not for idle CPU time while code waits on databases or downstream services. That is the main difference for request-response workloads that spend much of their time waiting — server-side rendering, streaming APIs, webhooks, microservices and AI inference endpoints are the examples AWS gives.

Concurrency and cold starts. A single warm execution environment can serve multiple concurrent requests, which AWS says reduces cold starts by orders of magnitude. Responses can be streamed to clients incrementally with native HTTP streaming.

Limits at launch. Lambda Web Functions supports the Node.js runtime only, and is available in five regions: US East (N. Virginia), US East (Ohio), US West (Oregon), Asia Pacific (Tokyo) and Europe (Ireland).

A rename for everything else. With this launch, existing Lambda functions are renamed Lambda Event Functions. AWS stresses that this is a naming change only, with no code changes or redeployments required.

CloudFront in front. In a separate announcement the same day, Amazon CloudFront added Lambda Web Functions as an origin. That gives TLS termination at the edge, caching and custom domains with managed certificates, without changes to application code. CloudFront Origin Access Control can restrict the function so it is reachable only through CloudFront, which puts it behind CloudFront's network-layer DDoS protection and allows AWS WAF to be attached; AWS notes that credentials of applications that authenticate their own users reach the application unchanged. The CloudFront feature is available worldwide except the China region, at no additional charge.

Sources: AWS, "AWS Lambda announces Lambda Web Functions" — https://aws.amazon.com/about-aws/whats-new/2026/10/aws-lambda-web-functions ; "Amazon CloudFront now supports AWS Lambda Web Functions as an origin" — https://aws.amazon.com/about-aws/whats-new/2026/10/cloudfront-lambda-web-functions-origin