These are the most used paas tools and products used by small SaaS businesses.
Amazon Web Services offers reliable, scalable, and inexpensive cloud computing services
Platform as a service (PaaS) that enables developers to build, run, and operate applications entirely in the cloud
Build, innovate, and scale with Google Cloud Platform
Microsoft Azure is an open, flexible, enterprise-grade cloud computing platform
A unified platform to build and run all your apps and websites with free SSL, a global CDN, private networks and auto deploys from Git
A European Cloud Computing company proposing a complete & simple public Cloud Ecosystem