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Mastering ChatGPT and OpenAI APIs with C#

Name: Mastering ChatGPT and OpenAI APIs with C#
Rating: 4.6 (30 reviews)

Build Generative AI-powered Blazor Web Apps—using both HttpClient and OpenAI's official .NET Library

Created byTom Liao

Last updated 5/2026

English

What you'll learn

Understand the concept of GPT and ChatGPT
Access OpenAI API via your own HTTPClient methods
Use the Chat Completion API with the OpenAI .NET library
Trigger external functions using Tools
Use the Image API with the OpenAI .NET library
Trigger multiple external Tools to complete complicate tasks
Learn the structure and meaning of parameters of OpenAI API
Learn how to send prompt and receive responses via non-streaming mode
Learn how to send prompt and receive responses via streaming mode
Know the difference between synchronous and asynchronous mode
Learn how to debug API connection issues
Develop two working GPT-enabled Blazor Server Apps
Learn the differences between .NET 7 and .NET 8 of Blazor technologies

Course content

10 sections • 63 lectures • 7h 0m total length

Introduction of this course3:53
The introduction of this course.
About the tutor - Just Go For It!2:22
The introduction of the course tutor.
Course name changed!0:32

Qick start12:11
The quick start video demonstrates how to utilize the info provided by ChatGPT to create a working C# Blazor Server App to access OpenAI API.
Codes generated by ChatGPT1:59
The full content of the steps provided by ChatGPT for creating a working Blazor Server App to access OpanAI API. (ps: These steps contain some minor errors, the corrective actions are provided in the previous video.)
How does your first GPT app work?11:51
A detailed explanation of how the Blazor Server App created earlier works.
Secure API Key7:10
An introduction of how to protect the secret API key in your app.
Code sample download for section 4 to 60:38
The project file is used in sections 4 to 6.
Quiz

Prompt - The Request Body8:08
The explanation of the parameters of the request body (aka Prompt) needed for the OpenAI API.
Response - The Chat Completion Object6:54
The explanation of the parameters of a chat completion object needed for the OpenAI API.
Develop C# Chat Completion Classes7:01
Steps to create chat completion classes using C#.
Modify C# Chat Completion Method8:08
Steps to modify the Chat Completion method provided by ChatGPT for better usage.
Finish_reason and Usage Tokens9:32
Explanation of the parameters, finish_reason, and usage tokens.
Beautify The Chat Page Style15:41
Steps to beautify front page of the Blazor Server App.
Quiz

What is streaming mode6:47
The explanation of what streaming mode is and how it works.
Modify request body classes for streaming mode1:34
Add new property for the request body class to activate streaming mode.
Create chat completion chunk classes3:48
Create classes used to receive chat completion chunks from the chat completion API under the streaming mode.
Create chat completion stream method8:45
Create a new IAsyncEnumerable method to process transactions with the chat completion API in streaming mode.
Modify front-end function for streaming mode9:37
Modify the index.razor page to reflect the change for processing the streaming mode.
Convert markdown characters to HTML6:33
Create the method to convert markdown characters included in the chat completion chunk objects into HTML tags.
Display usage info of streaming mode5:25
Display the token usage info on the front-end to the users
Conduct error handling6:38
Add the error handling methods to manage API exceptions.
Quiz

Hello World using the official .NET Library9:31
The first "Hello World!" code using the official OpenAI .NET Library. Connection methods used in this video are non-streaming mode.
Hello World in streaming mode6:47
Modify the non-streaming "Hello World!" program into the streaming mode by using the asynchronous streaming methods of the official .NET Library.
The official library vs the API reference4:47
Explain the differences between the API we created from scratch shown in the previous videos and the official OpenAI .NET Library.
Create a new Blazor Web App7:51
Create a new outfit for the new .NET 8 Blazor Web App that are going to be used with the OpenAI .NET Library.
Install and register the OpenAI package7:49
Install the OpenAI .NET Library from the NuGet package management.
Access the API in non-streaming mode10:01
Build the non-streaming API access methods using the official .NET Library.
Access the API in streaming mode10:12
Build the asynchronous streaming API access methods using the official .NET Library.
Retrieve Finish reason and Usage info4:39
Retrieve the Finish Reason and the token Usage info by using the official .NET Library.
Apply API Options and System messages5:08
Add extra option settings and system messages to the function call using the official .NET Library.
Quiz

What is Tool and how does it work6:07
ToolCalls enable GPT to call your external functions dynamically.
Tool Calls for synchronous non-streaming mode9:58
Implements tool calls in non-streaming sync API with loop logic.
Tool Calls for asynchronous non-streaming mode2:19
Adapts tool call logic for async non-streaming API behavior.
Use multiple tools together7:35
Demonstrates triggering multiple tools at once.
Tools Helper Classes1:52
Introduces helper classes to build streaming ToolCalls incrementally.
Tool Calls for synchronous streaming mode5:38
Implements synchronous streaming with support for ToolCalls processing.
Tool Calls for asynchronous streaming mode8:52
Implements asynchronous streaming with support for ToolCalls processing.
Create Tool Registry for multiple ToolCalls10:05
Centralizing tool registration via ToolRegistry for reusable integration.
Tool Choices for enforcing Tool Calls6:30
Options and limitations in enforcing tool usage.
Quiz

Important update note of the Image API2:10
Concept of image generation8:00
Explains the core concepts of OpenAI’s Image API, compares DALL·E and gpt-image-1 models, and clarifies their capabilities, limitations, costs, and usage scenarios before coding.
Prepare the project template5:29
Prepares a clean Blazor project template for image generation.
Generate images with a cloud URL output10:47
Generate images using OpenAI's Image API with cloud URL output.
Thumbnail and image modal8:06
Improve image UI with loading dots and thumbnail previews in Blazor.
Apply image options4:39
Configure DALL·E 3 image output using quality, size, style, and format options.
Generate images as Base64-encoded data12:19
Generate Base64 images, embed them in Blazor UI, and preview via a modal.
Generate images and save to local files9:45
Convert Base64 image data into local server-side image files for persistent access.
Integrate Image API to Tool Calls13:36
Integrate the Image API as a ToolCall for multi-tool Chat Completion workflows.
Display image modal via JS interop8:16
Use Blazor JS interop to trigger image modals from inline .NET code.
Remember conversation context6:18
Enable multi‑turn memory by sending the full chat history to the model.
Generate multiple images16:03
Generate multiple Base64 images in one request using the gpt-image-1 model
One prompt triggers multiple tools and images14:10
Generate multiple images by combining results from multiple tools in one prompt.
Quiz

Requirements

The enthusiasm for learning GenAI using C# (MUST)
Basic knowledge of C# programming (MUST)
Basic knowledge of ASP .Net Core web development (nice to have)

Description

Learn how to connect your C# applications to OpenAI's APIs—build real-world Blazor Web Apps using raw HTTPClient and the official .NET SDK. No Python needed!

Are you a C# developer eager to explore the exciting world of Generative AI but feel left behind in the Python-centric ecosystem?

This course is made just for you.

In this hands-on course, you'll learn how to connect your C# applications to OpenAI's ChatGPT API and build fully functional Blazor Web Apps powered by Generative AI. Whether you prefer using HttpClient to make raw RESTful API calls or want to leverage the official OpenAI .NET Library, this course covers both approaches in detail.

What makes this course special:

No need to switch to Python—learn how to build GenAI apps entirely with C#
Step-by-step guidance on setting up your OpenAI account, API key, and environment
Build interactive web applications using .NET 8 and Blazor
Deep dive into the Chat Completion API, including parameter configuration and streaming mode
Real project walkthroughs with clear, beginner-friendly explanations
Learn how to enrich GPT's capabilities by enabling it to trigger your own custom C# functions using the Tool Call mechanism.

What will you learn?

The following lists the main topics of this course:

A GPT course for C# developers – A brief introduction to the course and your instructor.
Intro to GPT, ChatGPT, and OpenAI API – Understand the evolution of ChatGPT and the different types of APIs available.
Preparing the prerequisites – Learn how to set up an OpenAI account, create a payment method, and generate an API key.
Quick Start – Use ChatGPT with C# to build your first Blazor Server App that accesses the OpenAI API.
Chat Completion API – Understand required parameters and improve the UI/UX of the Blazor app created earlier.
Streaming Mode – Learn how to receive chat completion chunks by enabling streaming in the API.
OpenAI .NET Library - Chat Completion API – Learn how to install the official OpenAI .NET Library and how to use the Chat Completion API to chat.
OpenAI .NET Library – Tools – Learn to use ToolCalls to execute external functions in all chat modes with .NET.
OpenAI .NET Library – Image API – Learn how to use the Image API to generate images with different models, and how to let the Chat Completion API call the Image API through tools to create images.
What's next? – A brief look at further learning directions after finishing the course.

Who is this course for?

C# developers ready to leap into Generative AI
Engineers looking to integrate ChatGPT into their C# applications or tools
Developers interested in mastering Blazor Web App development alongside AI

Prerequisites:

This course is marked as "all levels"—from the perspective of learning GenAI development with C#. However, the following background is recommended:

The enthusiasm for learning GenAI using C# (MUST)
Basic knowledge of C# programming (MUST)
Basic knowledge of ASP.NET Core web development (Nice to have)

Who this course is for:

Anyone who wants to bring ChatGPT capability to C# applications.
All C#ers (CSharpers) or C#ers wanna be!

Mastering ChatGPT and OpenAI APIs with C#

What you'll learn

Explore related topics

Course content

A GPT course for C# developers3 lectures • 7min

Intro of GPT, ChatGPT and OpenAI API4 lectures • 20min

Preparing the prerequisites5 lectures • 10min

Quick Start5 lectures • 34min

Chat Completion API6 lectures • 55min

Chat Completion API - Streaming mode8 lectures • 49min

OpenAI .NET Library - Chat Completion API9 lectures • 1hr 7min

OpenAI .NET Library - Tools9 lectures • 59min

OpenAI .NET Library - Image API13 lectures • 2hr

What's next?1 lecture • 1min

Requirements

Description

Who this course is for: