Introduction
OpenAI just gave developers superpowers.
With the new ChatGPT Apps SDK, you can now build apps that run inside ChatGPT itself — not as external integrations, but as native experiences within the chat interface.
This changes everything for developers, startups, and product builders. ChatGPT is no longer just an AI assistant — it’s a platform where your apps can live, interact with users, and leverage ChatGPT’s intelligence directly.
If the App Store created the mobile economy, ChatGPT is creating the AI App Economy.
In this guide, we’ll break down how to build, deploy, and publish your own app inside ChatGPT — step by step.
Understanding ChatGPT Apps
A ChatGPT App is essentially a mini-application hosted inside ChatGPT’s environment. It can:
Execute logic or API calls
Interact with users through natural language
Access data (with permissions)
Use ChatGPT’s reasoning, memory, and context
Run continuously or on-demand
These apps live inside ChatGPT’s interface, meaning users can discover, install, and run your app directly within their chat sessions.
Architecture Overview
A ChatGPT app consists of three main components:
| Component | Description | Example |
|---|
| Manifest File | Defines your app name, version, permissions, and endpoints. | app.yaml |
| API/Backend Logic | The brain of your app. This can run on your own server, cloud function, or local endpoint. | app.py, index.js |
| Chat Interface | How users interact with your app through ChatGPT. | User ↔ ChatGPT ↔ Your API |
When users invoke your app, ChatGPT handles the conversation flow and calls your API when required.
Step-by-Step: Building Your First ChatGPT App
Step 1: Set Up Your Environment
Sign in to your OpenAI Developer Account.
Ensure you have ChatGPT Plus or Team plan access.
Install the OpenAI CLI:
npm install -g openai
Initialize your project:
openai init my-chatgpt-app
cd my-chatgpt-app
Step 2: Create Your App Manifest
In your project folder, create a file named ai-plugin.json or manifest.yaml:
{"schema_version": "v1","name_for_human": "Weather Insights","name_for_model": "weather_app","description_for_human": "Get real-time weather updates and forecasts directly inside ChatGPT.","description_for_model": "Provides weather data via OpenWeather API.","auth": {
"type": "none"},"api": {
"type": "openapi",
"url": "https://yourdomain.com/openapi.yaml"},"logo_url": "https://yourdomain.com/logo.png","contact_email": "[email protected]","legal_info_url": "https://yourdomain.com/legal"}
This manifest defines your app identity, endpoints, and permissions.
Step 3: Build the Backend (Your Logic Layer)
Example using Node.js + Express:
import express from "express";
import fetch from "node-fetch";
const app = express();
app.get("/weather", async (req, res) => {
const { city } = req.query;
const apiKey = process.env.OPENWEATHER_KEY;
const response = await fetch(`https://api.openweathermap.org/data/2.5/weather?q=${city}&appid=${apiKey}`);
const data = await response.json();
res.json({
summary: `Current temperature in ${city} is ${(data.main.temp - 273.15).toFixed(1)}°C with ${data.weather[0].description}.`
});
});
app.listen(3000, () => console.log("Weather App running on port 3000"));
Deploy this to any cloud provider (Vercel, Azure, AWS, etc.).
Step 4: Define Your OpenAPI Spec
Create an openapi.yaml file describing your endpoints.
openapi: 3.0.1info:title: Weather Insights APIversion: 1.0.0servers:- url: https://yourdomain.compaths:/weather:
get:
summary: Get weather info
parameters:
- name: city
in: query
required: true
schema:
type: string
responses:
"200":
description: Successful response
This lets ChatGPT understand how to interact with your app.
Step 5: Test Your App in ChatGPT
Go to ChatGPT > Settings > Developer Mode.
Load your manifest URL (e.g. https://yourdomain.com/ai-plugin.json).
ChatGPT will automatically recognize and connect your app.
Now type:
“Ask Weather Insights for the forecast in New York.”
You’ll see your app respond directly inside ChatGPT — just like a built-in feature.
Step 6: Publish to ChatGPT App Directory
Once tested, you can submit your app to OpenAI’s App Directory.
Prepare:
Once approved, your app becomes discoverable by millions of users.
Example Use Cases
| Category | Example | Value |
|---|
| Productivity | Task planner, code generator | Automate daily workflows |
| Finance | Crypto tracker, stock alerts | Real-time data + insights |
| Learning | Quiz assistant, language tutor | Personalized education |
| Health | Fitness coach, diet planner | Goal tracking |
| Entertainment | Trivia, music selector | Interactive fun |
Security & Permissions
Each app must clearly define:
OpenAI enforces sandboxing and opt-in permissions for safety.
Monetization Opportunities
Soon developers will be able to:
Offer paid apps or premium tiers
Charge per use or subscription
Integrate third-party payment APIs
This is the birth of the AI App Economy, where developers can monetize directly within ChatGPT’s ecosystem.
Final Thoughts
The ability to host and build apps inside ChatGPT changes everything.
Developers now have a new platform — a way to combine natural language, APIs, and logic into a single seamless user experience.
At C# Corner, we believe this shift will spark a new generation of intelligent software — powered by developers who understand both code and conversation.
If you’re a developer, this is your signal.
Start building inside ChatGPT today — the future of AI apps is here.