MediatR 14.0.0-beta-1

MediatR

CI NuGet NuGet MyGet (dev)

Simple mediator implementation in .NET

In-process messaging with no dependencies.

Supports request/response, commands, queries, notifications and events, synchronous and async with intelligent dispatching via C# generic variance.

Examples in the wiki.

Installing MediatR

You should install MediatR with NuGet:

Install-Package MediatR

Or via the .NET Core command line interface:

dotnet add package MediatR

Either commands, from Package Manager Console or .NET Core CLI, will download and install MediatR and all required dependencies.

Using Contracts-Only Package

To reference only the contracts for MediatR, which includes:

  • IRequest (including generic variants)
  • INotification
  • IStreamRequest

Add a package reference to MediatR.Contracts

This package is useful in scenarios where your MediatR contracts are in a separate assembly/project from handlers. Example scenarios include:

  • API contracts
  • GRPC contracts
  • Blazor

Registering with IServiceCollection

MediatR supports Microsoft.Extensions.DependencyInjection.Abstractions directly. To register various MediatR services and handlers:

services.AddMediatR(cfg => cfg.RegisterServicesFromAssemblyContaining<Startup>());

or with an assembly:

services.AddMediatR(cfg => cfg.RegisterServicesFromAssembly(typeof(Startup).Assembly));

This registers:

  • IMediator as transient
  • ISender as transient
  • IPublisher as transient
  • IRequestHandler<,> concrete implementations as transient
  • IRequestHandler<> concrete implementations as transient
  • INotificationHandler<> concrete implementations as transient
  • IStreamRequestHandler<> concrete implementations as transient
  • IRequestExceptionHandler<,,> concrete implementations as transient
  • IRequestExceptionAction<,>) concrete implementations as transient

This also registers open generic implementations for:

  • INotificationHandler<>
  • IRequestExceptionHandler<,,>
  • IRequestExceptionAction<,>

To register behaviors, stream behaviors, pre/post processors:

services.AddMediatR(cfg => {
    cfg.RegisterServicesFromAssembly(typeof(Startup).Assembly);
    cfg.AddBehavior<PingPongBehavior>();
    cfg.AddStreamBehavior<PingPongStreamBehavior>();
    cfg.AddRequestPreProcessor<PingPreProcessor>();
    cfg.AddRequestPostProcessor<PingPongPostProcessor>();
    cfg.AddOpenBehavior(typeof(GenericBehavior<,>));
    });

With additional methods for open generics and overloads for explicit service types.

Setting the license key

You can set the license key when registering MediatR:

services.AddMediatR(cfg => 
{
    cfg.LicenseKey = "<license key here>";
})

Or if not using Microsoft.Extensions.DependencyInjection:

Mediator.LicenseKey = "<license key here>";

[!TIP] The license key does not need to be set on client applications (such as Blazor WASM). Turn off the license warning by configuring logging in your logging start configuration: builder.Logging.AddFilter("LuckyPennySoftware.MediatR.License", LogLevel.None);

You can register for your license key at MediatR.io

Showing the top 20 packages that depend on MediatR.

Packages Downloads
MediatR.Extensions.Microsoft.DependencyInjection
MediatR extensions for ASP.NET Core
 141
MediatR.Extensions.Microsoft.DependencyInjection
MediatR extensions for ASP.NET Core
 142
MediatR.Extensions.Microsoft.DependencyInjection
MediatR extensions for ASP.NET Core
 143
MediatR.Extensions.Microsoft.DependencyInjection
MediatR extensions for ASP.NET Core
 146
MediatR.Extensions.Microsoft.DependencyInjection
MediatR extensions for ASP.NET Core
 147
MediatR.Extensions.Microsoft.DependencyInjection
MediatR extensions for ASP.NET Core
 148
MediatR.Extensions.Microsoft.DependencyInjection
MediatR extensions for ASP.NET Core
 150
MediatR.Extensions.Microsoft.DependencyInjection
MediatR extensions for ASP.NET Core
 151
MediatR.Extensions.Microsoft.DependencyInjection
MediatR extensions for ASP.NET Core
 153
MediatR.Extensions.Microsoft.DependencyInjection
MediatR extensions for ASP.NET Core
 154
MediatR.Extensions.Microsoft.DependencyInjection
MediatR extensions for ASP.NET Core
 156
MediatR.Extensions.Microsoft.DependencyInjection
MediatR extensions for ASP.NET Core
 158
MediatR.Extensions.Microsoft.DependencyInjection
MediatR extensions for ASP.NET Core
 159
MediatR.Extensions.Microsoft.DependencyInjection
MediatR extensions for ASP.NET Core
 160
MediatR.Extensions.Microsoft.DependencyInjection
MediatR extensions for ASP.NET Core
 175
MediatR.Extensions.Microsoft.DependencyInjection
MediatR extensions for ASP.NET Core
 326
MediatR.Extensions.Microsoft.DependencyInjection
MediatR extensions for ASP.NET Core
 727

.NET Framework 4.6.2

.NET Standard 2.0

.NET 10.0

.NET 9.0

.NET 8.0

Version Downloads Last updated
14.2.0 19 07/03/2026
14.1.0 65 03/04/2026
14.0.0 174 12/04/2025
14.0.0-beta-1 79 11/21/2025
13.1.0 95 10/25/2025
13.0.0 504 07/04/2025
12.5.0 159 04/05/2025
12.4.1 588 09/13/2024
12.4.0 351 08/03/2024
12.3.0 170 06/27/2024
12.2.0 277 02/04/2024
12.1.1 144 02/09/2024
12.0.1 161 07/21/2024
12.0.0 43 02/24/2026
11.1.0 161 02/04/2024
11.0.0 306 02/04/2024
10.0.1 226 02/04/2024
10.0.0 172 07/21/2024
9.0.0 159 02/05/2024
8.1.0 157 07/21/2024
8.0.2 152 07/21/2024
8.0.1 144 07/21/2024
8.0.0 148 07/21/2024
7.0.0 150 07/21/2024
6.0.0 164 07/21/2024
5.1.0 142 07/21/2024
5.0.1 148 07/21/2024
5.0.1-alpha-0002 157 07/21/2024
5.0.1-alpha-0001 140 07/21/2024
4.1.0 166 07/21/2024
4.0.1 150 07/21/2024
4.0.0 158 07/21/2024
4.0.0-alpha-0002 166 07/21/2024
4.0.0-alpha 164 07/21/2024
3.0.1 162 07/21/2024
3.0.0 153 07/21/2024
2.1.0 153 07/21/2024
2.1.0-beta-19 153 07/21/2024
2.0.2 138 07/21/2024
2.0.1 145 07/21/2024
2.0.0 137 07/21/2024
2.0.0-beta-005 137 07/21/2024
2.0.0-beta-004 155 07/21/2024
2.0.0-beta-003 141 07/21/2024
2.0.0-beta-002 149 07/21/2024
2.0.0-beta-001 150 07/21/2024
1.0.0 155 07/21/2024
0.5.0 152 07/21/2024
0.4.0 133 07/21/2024
0.3.0 133 07/21/2024
0.2.0 145 07/21/2024
0.1.0 143 07/21/2024