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