AWS Launches Lambda Web Functions for Standard HTTP Applications

AWS has introduced Lambda Web Functions, a new compute form factor that enables developers to run standard HTTP web applications on Lambda without rewriting code into event handlers. This addition complements existing Lambda Event Functions and Lambda MicroVMs, all built on the same Firecracker isolation technology but designed for different programming models.

Programming Models and Billing

Lambda Web Functions use an HTTP-native model with multi-concurrent execution and active CPU billing, making them suitable for web apps, API backends, and I/O-heavy workloads. Unlike the single-concurrent, wall-clock billing model of Event Functions, Web Functions allow a single execution environment to handle up to 128 concurrent requests. This approach reduces costs for I/O-bound tasks by metering only the CPU time actively used by the code, while memory is metered for the environment's lifetime.

Deployment and Global Routing

Developers can deploy standard frameworks like Express, Hono, Fastify, or Next.js using a single AWS CLI command. The service automatically handles scaling and multi-region distribution. By specifying multiple regions during deployment, Lambda configures latency-based routing through a single global URL, directing traffic to the region with the lowest latency. Traffic can also be shifted between immutable code revisions for canary deployments via API calls.

Integration and Availability

The service integrates with Amazon CloudFront to serve static assets from cache while routing dynamic requests to the Web Function. It supports CloudFront origin access control (OAC) for private origins, ensuring only authorized distributions can invoke the endpoint. Lambda Web Functions are available today in US East (N. Virginia), US East (Ohio), US West (Oregon), Asia Pacific (Tokyo), and Europe (Ireland), supporting Node.js 24 on Arm64.