AutoSDK

The goal of this project is to automate and minimize the effort of maintaining high-quality .NET SDKs generated based on OpenAPI and AsyncAPI specifications, mainly to strengthen the AI ecosystem within .NET. The code generated by this library is also actively used in dozens of our various SDKs of varying complexity levels and in the LangChain.NET project, which ensures that it is tested in various scenarios and is ready for them.
Inspired by NSwag ❤️.

🔥Features🔥

• Detects your TargetFramework and generates optimal code for it (including net6.0/net7.0/net8.0 improvements)
• Supports .Net Framework/.Net Standard
• Supports OpenAPI 3.1 specs via compatibility normalization (nullability, examples, const, unevaluatedProperties, tuple-style arrays, and string content keywords)
• Does not contain dependencies for modern versions of dotnet.
• Only System.Text.Json dependency for .Net Framework/.Net Standard
• Any generated methods provide the ability to pass a CancellationToken
• Allows partial generation (models only) or end points filtering
• Available under MIT license for general users and most organizations
• Uses https://github.com/microsoft/OpenAPI.NET for parsing OpenAPI specification
• Supports nullable enable/trimming/native AOT compilation/CLS compliance
• Tested on GitHub 220k lines OpenAPI specification
• Supports OneOf/AnyOf/AllOf/Not schemas
• Supports Enums for System.Text.Json
• Supports AsyncAPI specs for WebSocket client generation (send/receive methods, cross-namespace schema referencing)
• Supports SSE (Server-Sent Events) through the application/x-ndjson content type
• Uses Incremental Source Generators for efficient generation and caching.
• Efficient O(n) implementation, fully suitable for large/super large OpenAPI specifications
• Used in 10+ real SDKs and adapted to solve various problems

🚀Quick start🚀

CLI (Recommended)

You can use the CLI to generate the code.

dotnet tool install --global autosdk.cli --prerelease
rm -rf Generated
autosdk generate openapi.yaml \
    --namespace Namespace \
    --clientClassName YourApi \
    --targetFramework net8.0 \
    --output Generated

It will generate the code in the "Generated" subdirectory.
It also will include polyfills for .Net Framework/.Net Standard TargetFrameworks.

HTTP Artifacts

autosdk http emits executable request files for regular OpenAPI path operations. It also surfaces response links and callbacks as commented documentation blocks next to the owning operation, and writes root-level OpenAPI webhooks to webhooks.http as inbound contract documentation instead of outbound client calls.

OpenAPI 3.1 Compatibility

AutoSDK normalizes the OpenAPI 3.1 / JSON Schema 2020-12 keywords it can translate cleanly into the current generation pipeline, including unevaluatedProperties, prefixItems, unevaluatedItems, contentEncoding, and contentMediaType.

Keywords that are still not representable in the current .NET model pipeline, such as patternProperties and contains/minContains/maxContains, now fail fast with a targeted error instead of being silently ignored.

Vendor Extension Compatibility

When AutoSDK_UseExtensionNaming or --use-extension-naming is enabled, AutoSDK consumes a curated set of third-party SDK metadata instead of treating every vendor extension as noise.

Concern	Supported today	Intentionally ignored for now
Naming and grouping	x-fern-sdk-method-name, x-fern-sdk-group-name, x-fern-type-name, x-oaiMeta.name, x-speakeasy-name-override, x-speakeasy-group, x-stainless-naming for .NET / csharp names	x-speakeasy-model-namespace, non-.NET x-stainless-naming blocks
Filtering and deprecation	x-fern-ignore, x-hidden, x-speakeasy-ignore, x-stainless-skip when it explicitly targets .NET, x-speakeasy-deprecation-message, x-stainless-deprecation-message	language skips for other ecosystems
Enum metadata	x-enum-varnames, x-enum-descriptions, x-fern-enum, x-speakeasy-enums, x-speakeasy-enum-descriptions	x-speakeasy-enum-format
Examples and docs	x-codeSamples, x-displayName, x-label	language-specific doc overlays such as x-speakeasy-docs
Runtime behavior	x-stainless-const	pagination, retries, globals, server selection, auth/runtime hints, and liblab config-only metadata

That split is deliberate: AutoSDK consumes metadata that directly improves generated .NET names, docs, deprecations, and enum surfaces today, while broader runtime features stay tracked as separate issues instead of being silently half-implemented.

Source generator

• Install the package

dotnet add package AutoSDK.SourceGenerators

• Add the following optional settings to your csproj file to customize generation. You can check all settings here:

<ItemGroup Label="AutoSDK">
    <AdditionalFiles Include="$(MSBuildThisFileDirectory)../../../docs/openapi.yaml" AutoSDK_OpenApiSpecification="true" />
</ItemGroup>

<!-- All settings optional -->
<PropertyGroup Label="AutoSDK">
    <AutoSDK_Namespace>Ollama</AutoSDK_Namespace>
    <AutoSDK_ClassName>OllamaApi</AutoSDK_ClassName>

    <!-- By default, it generates all models/methods. You can disable this behavior using these properties -->
    <AutoSDK_GenerateSdk>false</AutoSDK_GenerateSdk>
    <AutoSDK_GenerateModels>true</AutoSDK_GenerateModels>
    <AutoSDK_GenerateMethods>true</AutoSDK_GenerateMethods>
    <AutoSDK_GenerateConstructors>true</AutoSDK_GenerateConstructors>
    <AutoSDK_IncludeOperationIds>getPet;deletePet</AutoSDK_IncludeOperationIds>
    <AutoSDK_ExcludeOperationIds>getPet;deletePet</AutoSDK_ExcludeOperationIds>
    <AutoSDK_IncludeModels>Pet;Model</AutoSDK_IncludeModels>
    <AutoSDK_ExcludeModels>Pet;Model</AutoSDK_ExcludeModels>
</PropertyGroup>

• It's all! Now you can build your project and use the generated code. You also can use IDE to see the generated code in any moment, this is a example for Rider:
  

Trimming support

CLI

CLI generates Trimming/NativeAOT compatible code by default.

Source generator

Since there are two source generators involved, we will have to create a second project so that the generator for the JsonSerializerContext will “see” our models

• Create new project for your models. And disable methods/constructors generation:

<PropertyGroup Label="AutoSDK">
    <AutoSDK_GenerateSdk>false</AutoSDK_GenerateSdk>
    <AutoSDK_GenerateModels>true</AutoSDK_GenerateModels>
    <AutoSDK_GenerateJsonSerializerContextTypes>true</AutoSDK_GenerateJsonSerializerContextTypes>
</PropertyGroup>

• Reference this project in your main project.
• Add SourceGenerationContext.cs file to your main project with the following content:

using System.Text.Json.Serialization;

namespace Namespace;

[JsonSourceGenerationOptions(DefaultIgnoreCondition = JsonIgnoreCondition.WhenWritingNull)]
[JsonSerializable(typeof(AutoSDKTrimmableSupport))]
internal sealed partial class SourceGenerationContext : JsonSerializerContext;

• Add the following settings to your main csproj file:

<PropertyGroup Label="AutoSDK">
    <AutoSDK_GenerateSdk>false</AutoSDK_GenerateSdk>
    <AutoSDK_GenerateMethods>true</AutoSDK_GenerateMethods>
    <AutoSDK_GenerateConstructors>true</AutoSDK_GenerateConstructors>
    <AutoSDK_JsonSerializerContext>Namespace.SourceGenerationContext</AutoSDK_JsonSerializerContext>
</PropertyGroup>

• Add these settings to your new and main csproj file to enable trimming(or use Directory.Build.props file):

<PropertyGroup Label="Trimmable" Condition="$([MSBuild]::IsTargetFrameworkCompatible('$(TargetFramework)', 'net6.0'))">
    <IsAotCompatible>true</IsAotCompatible>
    <EnableTrimAnalyzer>true</EnableTrimAnalyzer>
    <IsTrimmable>true</IsTrimmable>
    <SuppressTrimAnalysisWarnings>false</SuppressTrimAnalysisWarnings>
    <TrimmerSingleWarn>false</TrimmerSingleWarn>
</PropertyGroup>

• It's all! Now you can build your project and use the generated code with full trimming/nativeAOT support.

Known Errors

Generator error: "Could not write to output file 'Path/to/file'. Could not find part of the path"

This error happens if the generated file path is too long. This happens if you didn't activated long path support on windows. To enable it follow the offical docs: https://learn.microsoft.com/en-us/windows/win32/fileio/maximum-file-path-limitation?tabs=registry#registry-setting-to-enable-long-paths

AsyncAPI / WebSocket Support

AutoSDK can generate typed WebSocket clients from AsyncAPI 3.0 specifications, producing send/receive methods for each channel operation.

Basic Usage

autosdk generate asyncapi.yaml \
    --namespace MyApi.Realtime \
    --websocket-class-name MyRealtimeClient \
    --output Generated

This generates:

• A WebSocket client class with connect/disconnect lifecycle
• Typed Send* methods for publish operations
• Typed Receive* methods (via event callbacks) for subscribe operations
• All associated models, enums, and JSON converters

Cross-Namespace Schema Referencing

When an API has both REST (OpenAPI) and WebSocket (AsyncAPI) specs that share model types, you can generate them into separate namespaces while avoiding model duplication:

# Step 1: Generate REST API (models + HTTP client) in main namespace
autosdk generate openapi.yaml \
    --namespace MyApi \
    --clientClassName MyApiClient \
    --output Generated

# Step 2: Generate WebSocket client referencing existing REST types
autosdk generate asyncapi.yaml \
    --namespace MyApi.Realtime \
    --websocket-class-name MyRealtimeClient \
    --types-namespace MyApi \
    --generate-models false \
    --json-serializer-context MyApi.SourceGenerationContext \
    --output Generated

Key options:

• --types-namespace <ns> — Generated WebSocket client uses global::<ns>.{TypeName} references instead of its own namespace
• --generate-models false — Skips model/enum/converter generation (they already exist in the types namespace)
• --json-serializer-context <ctx> — References an existing JsonSerializerContext from the types namespace
• --websocket-class-name <name> — Overrides the generated WebSocket client class name

Note: AsyncAPI schema names must match the target namespace's type names. If they differ (e.g., OpenAI where AsyncAPI uses different names), use separate namespaces with full model generation instead.

Real-world examples

• tryAGI/OpenAI — REST API + Realtime WebSocket API
• tryAGI/ElevenLabs — REST API + Realtime Speech-to-Text WebSocket API
• tryAGI/Xai — REST API + Realtime Voice Agent WebSocket API

🤖 Claude Code Skill

AutoSDK is available as a Claude Code skill via skills.sh, enabling AI-assisted SDK generation directly from your terminal.

Install

npx skills add tryAGI/AutoSDK@generating-dotnet-sdks

Usage

Once installed, you can use natural language prompts in Claude Code like:

• "Generate a C# SDK from this OpenAPI spec"
• "Scaffold a new AutoSDK project for the Stripe API"
• "Help me customize the generated client with streaming support"

Claude Code will use the skill's knowledge of AutoSDK CLI options, project conventions, and customization patterns to produce correct commands and code.

What's included

The skill provides Claude Code with detailed knowledge of:

• CLI commands and all their options (generate, init, http, ai spec-from-docs)
• Standard project structure and the generate.sh regeneration pattern
• AsyncAPI / WebSocket client generation and cross-namespace schema referencing
• Post-generation customization (partial classes, client hooks, trimming support)
• Troubleshooting common issues

Skill source: skills/generating-dotnet-sdks/

📚Examples of use in real SDKs📚

• https://github.com/tryAGI/OpenAI — REST + WebSocket (AsyncAPI)
• https://github.com/tryAGI/ElevenLabs — REST + WebSocket (AsyncAPI)
• https://github.com/tryAGI/Xai — REST + WebSocket (AsyncAPI)
• https://github.com/tryAGI/Ollama
• https://github.com/tryAGI/Anthropic
• https://github.com/tryAGI/LangSmith
• https://github.com/tryAGI/Replicate
• https://github.com/tryAGI/DeepInfra
• https://github.com/tryAGI/Leonardo
• https://github.com/HavenDV/GitHub.NET