Heroku CI vs Test Kitchen: What are the differences?

What is Heroku CI? Fast, low-setup CI that’s easy to use. On every push to GitHub, Heroku CI runs your tests in a disposable Heroku app, so there’s never a wait time for a free CI worker. Tests run fast, on Performance dynos.

What is Test Kitchen? Integration tool for developing and testing infrastructure code and software on isolated target platforms. Test Kitchen has a static, declarative configuration in a .kitchen.yml file at the root of your project. It is designed to execute isolated code run in pristine environments ensuring that no prior state exists. A plugin architecture gives you the freedom to run your code on any cloud, virtualization, or bare metal resources and allows you to write acceptance criteria in whatever framework you desire.

Heroku CI and Test Kitchen can be categorized as "Continuous Integration" tools.

Test Kitchen is an open source tool with 1.62K GitHub stars and 543 GitHub forks. Here's a link to Test Kitchen's open source repository on GitHub.