What are you looking for if you want to create a new software application without worrying about purchasing necessary underlying hardware infrastructure?

When considering the creation of a new software application without the need to invest in or manage the underlying hardware infrastructure, utilizing a Platform as a Service (PaaS) is the optimal choice. PaaS provides a cloud-based platform that includes not only the hardware infrastructure needed to run applications but also the development tools and services required for software development and deployment.

This environment allows developers to focus primarily on writing code and developing the application without the complexities of managing servers, storage, networking, or other infrastructure components. PaaS often includes built-in software development kits (SDKs), application hosting, and various middleware services, streamlining the entire development process.

In contrast, Software as a Service (SaaS) involves using applications that are managed by third-party vendors and accessed over the internet, which does not facilitate custom application development. Infrastructure as a Service (IaaS) involves renting virtualized computing resources and requires management of the operating systems and applications, which does not eliminate the responsibility from the developer concerning the underlying infrastructure. An on-premise solution would entail maintaining and managing the hardware and infrastructure within the organization itself, which contradicts the goal outlined in the question.