OpenAPI2JsonSchema 2.0.0

dotnet add package OpenAPI2JsonSchema --version 2.0.0
NuGet\Install-Package OpenAPI2JsonSchema -Version 2.0.0
This command is intended to be used within the Package Manager Console in Visual Studio, as it uses the NuGet module's version of Install-Package.
<PackageReference Include="OpenAPI2JsonSchema" Version="2.0.0" />
For projects that support PackageReference, copy this XML node into the project file to reference the package.
paket add OpenAPI2JsonSchema --version 2.0.0
#r "nuget: OpenAPI2JsonSchema, 2.0.0"
#r directive can be used in F# Interactive and Polyglot Notebooks. Copy this into the interactive tool or source code of the script to reference the package.
// Install OpenAPI2JsonSchema as a Cake Addin
#addin nuget:?package=OpenAPI2JsonSchema&version=2.0.0

// Install OpenAPI2JsonSchema as a Cake Tool
#tool nuget:?package=OpenAPI2JsonSchema&version=2.0.0


A library to create Json-Schemas from OpenAPI-specifications giving the possibility to include FluentValdiation rules in JsonSchemas.

Getting Started

Create OpenAPI-specifiation

First you will need to create an OpenAPI-specification, which you'll be translating to Json-Schema later.


If you use Swashbuckle this might look something like this:

Register services in Program.cs

builder.Services.AddSwaggerGen(c =>
        c.SwaggerDoc("v1", new OpenApiInfo {Title = "MyApplication", Version = "v1"});
        var xmlFile = $"{Assembly.GetExecutingAssembly().GetName().Name}.xml";
        var xmlPath = Path.Combine(AppContext.BaseDirectory, xmlFile);

In this example, an OpenAPI-specification is created. In order to keep Data Annotations out of its model, this examples uses FluentValidationRules, that can be added easily using the last line in the example above from Swashbuckle.FluentValidation.

Enable middleware in Program.cs


if (app.Environment.IsDevelopment())
    app.UseSwaggerUI(c => { c.SwaggerEndpoint("/swagger/v1/swagger.json", "MyApplication v1"); });


Install the library using NuGet-Package Manager:

Install-Package OpenAPI2JsonSchema

Dependency Injection

First import the following Package in Startup.cs:

using OpenApi2JsonSchema.DependencyInjection;
using OpenApi2JsonSchema.Configuration;

Now, in order to be able to use the library, simply add the following line to the ConfigureServices()-method in Startup.cs:

services.AddJsonSchemaGenerator(new JsonSchemaGeneratorConfiguration
                OpenApiFileDownloadPath = "swagger.json",
                OpenApiUrl = "http://localhost:61306/swagger/v1/swagger.json"

The JsonSchemaGeneratorConfiguration allows to specify the following optional properties:

  • OpenApiFileDownloadPath → Path where to save the downloaded file (ignored if caching is disabled)
  • OpenApiUrl → URL to the OpenAPI-specification
  • CachingDisabled → Specify wheter or not caching should be disabled. Default is false.

Note that if you don't specify an URL for the OpenAPI-specification here in ConfigureServices()-method, you will need to specify it whenever you use the JsonSchemaGenerator-instance.


You can generate a JsonSchema for any type using:

var schema = JsonSchemaGenerator.GetSchemaWithOpenApi<T>("<url-to-openapi-file>");

If not specified in Startup.cs, just replace <url-to-openapi-file> with the URL that points to your OpenAPI-JSON-file, otherwise pass no parameter.


Delete OpenAPI-file on Startup

Since the library downloads the specified OpenAPI-file and caches it for further usage, you can optionally delete the downloaded file on Startup by adding the following lines to the Configure()-method in Startup.cs:

app.UseOpenApi2JsonSchemaGenerator(new JsonSchemaGeneratorConfiguration
    OpenApiFileDownloadPath = "swagger.json"

Note that the if you did not set the DownloadPath to the OpenAPI-file in ConfigureServices()-method, you don't need to pass a parameter.

Product Compatible and additional computed target framework versions.
.NET net6.0 is compatible.  net6.0-android was computed.  net6.0-ios was computed.  net6.0-maccatalyst was computed.  net6.0-macos was computed.  net6.0-tvos was computed.  net6.0-windows was computed.  net7.0 was computed.  net7.0-android was computed.  net7.0-ios was computed.  net7.0-maccatalyst was computed.  net7.0-macos was computed.  net7.0-tvos was computed.  net7.0-windows was computed.  net8.0 was computed.  net8.0-android was computed.  net8.0-browser was computed.  net8.0-ios was computed.  net8.0-maccatalyst was computed.  net8.0-macos was computed.  net8.0-tvos was computed.  net8.0-windows was computed. 
Compatible target framework(s)
Included target framework(s) (in package)
Learn more about Target Frameworks and .NET Standard.

NuGet packages

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Version Downloads Last updated
2.0.0 341 2/10/2023
1.1.4 684 6/8/2020
1.1.3 535 6/3/2020
1.1.2 496 5/25/2020
1.1.1 521 3/25/2020
1.1.0 513 3/24/2020
1.0.0 513 3/20/2020

- Update to .NET 6
- Implement method chaining for DependencyInjection
- Add icon