Heroku

Cloud Application Platform

Heroku is a platform as a service (PaaS) that enables developers to build, run, and operate applications entirely in the cloud.

About

I've been using Heroku for a many years, it provides a great scaleable solution for any kind of application.

Heroku has support for many different languages and framework, with great documentation to get up and running quickly.

I have deployed applications with Laravel/PHP and Ruby on Rails, but there is support for so much more.

The free tier provides you enough resources to get your MVP built and launched, before you need to start paying for their services.  The free tier can also be used to host a staging version of your website to do testing before moving code into production.
Do you use a free product we've missed?