NRules 

Canonical rules model to define rules for the NRules rules engine.

Execution engine for the NRules rules engine.

Fluent DSL for authoring rules in C# with the NRules rules engine.

NRules is an open source rules engine for .NET that is based on the Rete matching algorithm with rules authored in C# using internal DSL.

Autofac integration for NRules

Business rules language for NRules rules engine.

JSON serialization for the NRules rules engine.

Rules unit testing harness for NRules.