The correct choice is AWS Lambda. It runs short backend code only when events occur and it requires no server provisioning or management.

AWS Lambda executes functions in response to triggers such as image uploads or API requests and it automatically scales and manages the underlying infrastructure so you pay only for execution time. This event driven, function as a service model matches the startup need for occasional short tasks without ongoing server operations.

Amazon EC2 is not appropriate because you must provision and manage virtual machine instances and handle scaling networking and operating system maintenance yourself which increases operational overhead.

Amazon ECS manages containers and orchestration and it still requires building container images and configuring deployments which is heavier than a simple function service.

AWS Fargate removes server management for containers but it remains a container based compute option rather than a function as a service and it is therefore less suited for tiny event driven code snippets.

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