With many ways of doing things in Salesforce, sometimes you do have to "reinvent the wheel", but if you do, you might as well do it in a configurable and scalable way. 

Join Manish Choudhari as he walks us through a Rule Engine he built to solve some unique business needs at Amazon, and how he has now turned this tool into something that is highly configurable and reusable.

The Rule Engine is a powerful tool similar to Process Builder, but it is executed an Apex context, and comes with a business-user friendly user interface. The UI helps in creating complex criteria based tools and can execute actions such as return a value, call an Apex method, and other things. This is a complete custom tool built from scratch but has a lot of potential to solve many business cases.