Nexum

Nexum

A modern CQRS library for .NET 10 / C# 14. Compile-time safe, zero reflection, ValueTask throughout. A MediatR successor built for observability and hot-path performance.

Get Started API Reference

Why Nexum

ValueTask throughout

Every handler returns ValueTask<T>. Synchronous paths allocate zero bytes — no Task heap overhead on the hot path, no state machines for trivial handlers.

Hybrid runtime + generators

The Runtime dispatcher works standalone without any Source Generator. Add Nexum.SourceGenerators and you get compile-time discovery, monomorphized pipelines, and Roslyn interceptors — up to 34% faster.

OpenTelemetry built-in

Every dispatch creates an Activity with structured tags. Metrics, distributed tracing, and exemplars work out of the box through any OTel-compatible backend.

Core concepts

Getting Started

Install the package and dispatch your first command.

Commands & Queries

Strict CQRS: ICommand, IQuery, IStreamQuery.

Notifications

Domain events with four publish strategies.

Pipeline Behaviors

Separate command/query pipelines, Russian doll model.

Stream Queries

First-class IAsyncEnumerable<T> support.

Source Generators

Tiered compile-time acceleration: Runtime → Compiled → Interceptors.

Dependency Injection

AddNexum(), assembly scanning, handler lifetimes.

Observability

OpenTelemetry tracing and metrics out of the box.

Result Pattern

Result<T, TError> with FluentValidation support.

ASP.NET Core

Minimal API endpoints, middleware, Problem Details.

Testing

NexumTestHost, fake dispatchers, behavior isolation.

Migration from MediatR

Gradual migration via adapters and Roslyn analyzer.

Benchmarks

18.96 ns command dispatch

0 B hot path allocations

2.1× faster than MediatR

28× less memory (notifications)

About

Nexum is developed by Wizard-Software and hosted on GitHub at Wizard-Software/nexum. MIT licensed.