How to Integrate OpenAI API in ASP.NET Core 10 Using C# – Step-by-Step Guide (2026)
A useful AI feature usually starts with a small job: rewrite a support reply, summarize a paragraph, or explain a piece of code. You do not need a chatbot framework to try one of those features in an ASP.NET Core application. This guide shows how to integrate the OpenAI API in ASP.NET Core 10 using C# . You will build one local POST endpoint, keep the API key on the server, and return a text response as JSON. How do you call OpenAI from ASP.NET Core 10? Install the official OpenAI NuGet package, store the API key in server-side configuration, register a ResponsesClient, and call CreateResponseAsync from an async endpoint. Validate the incoming prompt and return only the text your application needs. The browser calls your API; your server calls OpenAI. Scope: a local Minimal API for learning. It has input validation and a small shared request limit, but no user authentication or conversation history. Do not expose this demo publicly without adding access controls. Prerequisites an...
