平台即服务（platform as a service，缩写作PaaS）是一种云端运算服务，提供运算平台与解决方案堆叠即服务。在云端运算的典型层级中，平台即服务层介于软件即服务与基础设施即服务之间。

平台即服务提供用户能将云端基础设施部署与创建至用户端，或者借此获得使用编程语言、程序库与服务。用户不需要管理与控制云端基础设施，包含网络、服务器、操作系统或保存，但需要控制上层的应用程序部署与应用代管的环境。

PaaS将软件研发的平台做为一种服务，以软件即服务（SaaS）的模式交付给用户。因此，PaaS也是SaaS模式的一种应用。但是，PaaS的出现可以加快SaaS的发展，尤其是加快SaaS应用的开发速度。

Platform as a service (PaaS) is a category of cloud computing services that provides a platform allowing customers to develop, run, and manage applications without the complexity of building and maintaining the infrastructure typically associated with developing and launching an app. PaaS can be delivered in two ways: as a public cloud service from a provider, where the consumer controls software deployment with minimal configuration options, and the provider provides the networks, servers, storage, OS, 'middleware' (i.e.; java runtime, .net runtime, integration, etc.), database and other services to host the consumer's application; or as a private service (software or appliance)inside the firewall, or as software deployed on a public infrastructure as a service.