DotNetOpenApiExtract.Core 0.1.0

.NET 10.0 This package targets .NET 10.0. The package is compatible with this framework or higher.
There is a newer version of this package available.
See the version list below for details. 
dotnet add package DotNetOpenApiExtract.Core --version 0.1.0
                    


                    

                
NuGet\Install-Package DotNetOpenApiExtract.Core -Version 0.1.0
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="DotNetOpenApiExtract.Core" Version="0.1.0" />
For projects that support PackageReference, copy this XML node into the project file to reference the package. 
<PackageVersion Include="DotNetOpenApiExtract.Core" Version="0.1.0" />
                    


                            Directory.Packages.props
                        

                    

                
<PackageReference Include="DotNetOpenApiExtract.Core" />
                    


                            Project file
For projects that support Central Package Management (CPM), copy this XML node into the solution Directory.Packages.props file to version the package. 
paket add DotNetOpenApiExtract.Core --version 0.1.0
                    


                    

                
#r "nuget: DotNetOpenApiExtract.Core, 0.1.0"
#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. 
#:package DotNetOpenApiExtract.Core@0.1.0
#:package directive can be used in C# file-based apps starting in .NET 10 preview 4. Copy this into a .cs file before any lines of code to reference the package. 
#addin nuget:?package=DotNetOpenApiExtract.Core&version=0.1.0
                    


                            Install as a Cake Addin
                        

                    

                
#tool nuget:?package=DotNetOpenApiExtract.Core&version=0.1.0
                    


                            Install as a Cake Tool

DotNetOpenApiExtract

CLI tool that extracts OpenAPI specifications from compiled .NET assemblies (DLL + XML docs) using static reflection — no application startup required.

dotnet openapi-extract --assembly bin/Debug/net9.0/MyApi.dll --output openapi.json

Why

Standard OpenAPI generation tools (swagger tofile, Microsoft.AspNetCore.OpenApi) require the application to fully start — which means a real database, message queues, external APIs, background services, and all environment variables must be available. Without infrastructure, the app crashes and the spec is never generated.

DotNetOpenApiExtract solves this by reading metadata directly from the compiled DLL via MetadataLoadContext. It never executes any code from your assembly. All it needs is the build output directory.

This means you can generate OpenAPI specs:

  • In CI/CD without any infrastructure
  • On developer machines without Docker or databases running
  • From any .NET version (6, 7, 8, 9, 10) assembly

CLI Parameters

Parameter Required Default Description
--assembly <path> yes — Path to the compiled DLL
--output <path> no swagger.json Output file path
--format <json\|yaml> no json Output format
--title <string> no assembly name API title in the info block
--version <string> no v1 API version in the info block
--description <string> no — API description
--xml <path> no auto-detect Path to XML documentation file
--camel-case no true Use camelCase for property names
--enum-as-string no false Serialize enums as strings
--openapi-version <3.0\|3.1\|3.2> no 3.0 OpenAPI specification version
--exclude-path <prefix> no — Exclude paths by prefix (repeatable)

What It Extracts

  • Controllers ([ApiController], ControllerBase inheritance)
  • Routes ([Route], [HttpGet], [HttpPost], etc.) with full template resolution
  • Parameters ([FromRoute], [FromQuery], [FromBody], [FromHeader], [FromForm]) with [ApiController] inference
  • Responses ([ProducesResponseType], [SwaggerResponse]) with return type inference
  • Schemas from DTO classes — primitives, nullable, collections, dictionaries, enums, generics, inheritance, self-referencing types
  • Validation attributes ([Required], [StringLength], [Range], [RegularExpression], etc.)
  • JSON attributes ([JsonPropertyName], [JsonIgnore], [JsonRequired])
  • Swagger annotations ([SwaggerOperation], [SwaggerParameter], [SwaggerTag], [SwaggerSchema])
  • XML documentation (<summary>, <remarks>, <param>, <response>)
  • Nullable reference types via NRT attribute analysis
  • Description fallback chains: Swagger attrs > [Description] > XML docs

For the complete catalog of 650+ supported attributes and constructs, see OpenAPI Attributes Catalog.

Limitations

What Why
IOperationFilter, IDocumentFilter, ISchemaFilter Arbitrary C# code executed at runtime — cannot be analyzed statically
Conventional routing (MapControllerRoute) Routes defined in runtime code, not in attributes
Minimal API endpoints (app.MapGet(...)) Endpoints defined in Program.cs, not via controllers
Custom [JsonConverter] logic Converter behavior is arbitrary runtime code
[ModelBinder] custom binding Runtime behavior, not interpretable statically
Security schemes (AddSecurityDefinition) Configured programmatically in DI — use --exclude-path or config file
Runtime Swashbuckle filters Any filter that modifies the document at runtime is invisible to static analysis

Dependencies

Package Version Purpose
Microsoft.OpenApi 3.5.0 OpenAPI document model, JSON/YAML serialization, validation
Microsoft.OpenApi.YamlReader 3.5.0 YAML output support
System.Reflection.MetadataLoadContext 10.0.5 Load DLLs without executing code, read attributes and types
System.CommandLine 2.0.5 CLI argument parsing

Does not depend on: ASP.NET Core, Swashbuckle, Entity Framework, or any infrastructure packages.

Requirements

  • .NET 10 SDK (to run the tool)
  • The target assembly's build output directory with all reference DLLs (the tool needs them to resolve types)

Building

dotnet build
dotnet test

License

MIT

Product Compatible and additional computed target framework versions.
.NET net10.0 is compatible.  net10.0-android was computed.  net10.0-browser was computed.  net10.0-ios was computed.  net10.0-maccatalyst was computed.  net10.0-macos was computed.  net10.0-tvos was computed.  net10.0-windows was computed. 
Compatible target framework(s)
Included target framework(s) (in package)
Learn more about Target Frameworks and .NET Standard.

NuGet packages

This package is not used by any NuGet packages.

GitHub repositories

This package is not used by any popular GitHub repositories.

Version Downloads Last Updated
0.15.0 89 5/12/2026
0.14.0 98 4/30/2026
0.12.0 97 4/30/2026
0.11.0 108 4/29/2026
0.10.0 102 4/24/2026
0.9.0 98 4/22/2026
0.8.0 100 4/22/2026
0.7.0 95 4/20/2026
0.6.0 103 4/19/2026
0.5.0 98 4/19/2026
0.4.0 91 4/19/2026
0.3.0 91 4/19/2026
0.2.0 100 4/18/2026
0.1.0 110 3/24/2026