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Howard van Rooijen By Howard van Rooijen Co-Founder
OpenAPI Document Converters for Visual Studio 2017

In my previous post I documented a technical spike I carried out to see how I could take the OpenAPI.NET SDK and create a Custom Tool in Visual Studio, in particular a Single-File Generator, that could be used to improve the Azure Functions v1 local development experience. Since then the OpenAPI.NET SDK reached v1.0 and while I was at BUILD I decided to spent a little bit more time productionising the solution. I've migrated the solution to its own GitHub repo - Endjin.OpenAPI.Converters, fixed issues around supporting the new Common Project System, and changed the Custom Tool names to make a bit more sense:

  • to OpenAPI 2.0 JSON - Set Custom Tool to "ConvertToOpenApi_2_0_Json"
  • to OpenAPI 2.0 YAML - Set Custom Tool to "ConvertToOpenApi_2_0_Yaml"
  • to OpenAPI 3.0 JSON - Set Custom Tool to "ConvertToOpenApi_3_0_Json"
  • to OpenAPI 3.0 YAML - Set Custom Tool to "ConvertToOpenApi_3_0_Yaml"

The primary usage scenario for this tool is the authoring of OpenAPI files in local Azure Function (V1) projects in the easier to maintain YAML format and automatically generating the required swagger.json file.

To add a OpenAPI document to your Function v1 project add the following folder structure


Add a new file called swagger.yaml. On the property pane for this file, set the Custom Tool to equal "ConvertToOpenApi_2_0_Json". This will generate a swagger.json file.

Make sure you set the Build Action to "Content" and Copy to Output Directory to "Copy if newer" for the newly generated swagger.json file.

I've packaged up the extension into an easily installable VSIX package that can be downloaded from the releases tab on the GitHub repo. Please try it out and leave any feedback / issues on GitHub.

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Howard van Rooijen


Howard van Rooijen

Howard spent 10 years as a technology consultant helping some of the UK's best known organisations work smarter, before founding endjin in 2010. He's a Microsoft ScaleUp Mentor, and a Microsoft MVP for Azure and Developer Technologies, and helps small teams achieve big things using data, AI and Microsoft Azure.