MediatR 14.1.0

MediatR

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	108
MediatR.Extensions.Microsoft.DependencyInjection MediatR extensions for ASP.NET Core	110
MediatR.Extensions.Microsoft.DependencyInjection MediatR extensions for ASP.NET Core	114
MediatR.Extensions.Microsoft.DependencyInjection MediatR extensions for ASP.NET Core	116
MediatR.Extensions.Microsoft.DependencyInjection MediatR extensions for ASP.NET Core	117
MediatR.Extensions.Microsoft.DependencyInjection MediatR extensions for ASP.NET Core	118
MediatR.Extensions.Microsoft.DependencyInjection MediatR extensions for ASP.NET Core	119
MediatR.Extensions.Microsoft.DependencyInjection MediatR extensions for ASP.NET Core	120
MediatR.Extensions.Microsoft.DependencyInjection MediatR extensions for ASP.NET Core	121
MediatR.Extensions.Microsoft.DependencyInjection MediatR extensions for ASP.NET Core	122
MediatR.Extensions.Microsoft.DependencyInjection MediatR extensions for ASP.NET Core	123
MediatR.Extensions.Microsoft.DependencyInjection MediatR extensions for ASP.NET Core	127
MediatR.Extensions.Microsoft.DependencyInjection MediatR extensions for ASP.NET Core	129
MediatR.Extensions.Microsoft.DependencyInjection MediatR extensions for ASP.NET Core	138
MediatR.Extensions.Microsoft.DependencyInjection MediatR extensions for ASP.NET Core	290
MediatR.Extensions.Microsoft.DependencyInjection MediatR extensions for ASP.NET Core	614

Version	Downloads	Last updated
14.1.0	3	03/04/2026
14.0.0	56	12/04/2025
14.0.0-beta-1	32	11/21/2025
13.1.0	54	10/25/2025
13.0.0	379	07/04/2025
12.5.0	113	04/05/2025
12.4.1	530	09/13/2024
12.4.0	306	08/03/2024
12.3.0	135	06/27/2024
12.2.0	246	02/04/2024
12.1.1	121	02/09/2024
12.0.1	119	07/21/2024
12.0.0	10	02/24/2026
11.1.0	130	02/04/2024
11.0.0	251	02/04/2024
10.0.1	190	02/04/2024
10.0.0	128	07/21/2024
9.0.0	129	02/05/2024
8.1.0	120	07/21/2024
8.0.2	126	07/21/2024
8.0.1	116	07/21/2024
8.0.0	118	07/21/2024
7.0.0	121	07/21/2024
6.0.0	134	07/21/2024
5.1.0	113	07/21/2024
5.0.1	118	07/21/2024
5.0.1-alpha-0002	122	07/21/2024
5.0.1-alpha-0001	112	07/21/2024
4.1.0	128	07/21/2024
4.0.1	113	07/21/2024
4.0.0	120	07/21/2024
4.0.0-alpha-0002	131	07/21/2024
4.0.0-alpha	124	07/21/2024
3.0.1	126	07/21/2024
3.0.0	117	07/21/2024
2.1.0	127	07/21/2024
2.1.0-beta-19	121	07/21/2024
2.0.2	102	07/21/2024
2.0.1	118	07/21/2024
2.0.0	110	07/21/2024
2.0.0-beta-005	112	07/21/2024
2.0.0-beta-004	123	07/21/2024
2.0.0-beta-003	112	07/21/2024
2.0.0-beta-002	119	07/21/2024
2.0.0-beta-001	125	07/21/2024
1.0.0	119	07/21/2024
0.5.0	123	07/21/2024
0.4.0	104	07/21/2024
0.3.0	104	07/21/2024
0.2.0	111	07/21/2024
0.1.0	114	07/21/2024

MediatR 14.1.0

Readme

MediatR

Installing MediatR

Using Contracts-Only Package

Registering with IServiceCollection

Setting the license key

Used By

Dependencies

.NET Framework 4.6.2

.NET Standard 2.0

.NET 10.0

.NET 9.0

.NET 8.0

Versions

Registering with `IServiceCollection`