What HTTP method in a RESTful web service is typically used to replace a resource completely?

In RESTful web services, the HTTP method that is typically used to replace a resource completely is PUT. The PUT method is designed for updating an entire resource; when a client sends a PUT request, it is generally understood that the client intends to provide a complete representation of the resource, which will either create a new resource if it does not exist or replace the existing resource if it does.

This aligns with REST principles, where each method has a specific semantics. Unlike PATCH, which is used for partial updates to a resource, PUT requires that the client sends the entire resource representation. This makes PUT an idempotent operation—subsequent identical requests will have the same effect as a single one, ensuring clarity and predictability regarding how resources should be managed.

Other methods such as POST, which is typically used for creating new resources, and GET, which is used for retrieving resources without modifying them, do not serve the intended purpose of fully replacing a resource either. Thus, the definitiveness of the PUT method in fully replacing resources is what sets it apart and makes it the appropriate choice for this scenario.