Are OutSystems free?

it has both free and licenced versions, for personal environmet its free, but if you want enterprise version you need buy licence.

yes

There is a free edition of OutSystems which you can use for small personal apps. While there are no limits to the main functionality with the free edition, there are some limits to the infrastructure which make it impractical for use for mission critical enterprise apps. See here for details https://success.outsystems.com/Support/Licensing/What_is_an_OutSystems_Personal_Environment

It's free for a personal use, however if it escalates for an enterprise use it's paid

Outsystems is open resource for personal/trail use which provides 2gb of cloud data free to use. There are basic and standard packages for Subscription of Enterprise versions

It has a free version with limited features and for personal usage (training and community collaboration).