Higson.io - Hyperon is a BRMS, that was created with very large decisions and hyper-performance in mind. It stands out with the concept of the business domain which organizes the whole configuration in easy to manage way.
SAI360 - GRC Platforms
OptaPlanner - Mathematical optimization software
AuditBoard - AuditBoard is a platform that offers compliance and audit management that allows auditors to analyze, manage, and report the business operations.
Simple Rule Engine - DotNet simple BRMS XML rule engine
Axonify - Axonify is an Employee Knowledge Platform that provides e-learning solutions to the employees.