Build Hour: Apps in ChatGPT

Why It Matters

By enabling developers to publish interactive AI‑driven apps inside ChatGPT, OpenAI opens a scalable marketplace that can accelerate product innovation and give businesses direct access to millions of users through conversational interfaces.

Key Takeaways

• OpenAI launches ChatGPT Apps platform with SDK and marketplace.
• New Docs MCP server accelerates app development via AI‑first scaffolding.
• Developers can embed UI widgets and full‑screen components in ChatGPT.
• Public app submission flow enables global distribution of custom ChatGPT apps.
• Codex integration streamlines coding, reducing traditional development cycle.

Summary

The OpenAI Build Hour introduced the ChatGPT Apps platform, showcasing a suite of new tools—including an Apps SDK, a public app submission flow, and a marketplace—designed to let developers embed interactive experiences directly inside ChatGPT. Core announcements covered the launch of the Docs MCP server, which provides AI‑first scaffolding for rapid app creation, and a UI component library that standardizes widget look‑and‑feel across the ecosystem.

Presenters demonstrated real‑world use cases: the AllTrails app fetched dog‑friendly hiking routes, Adobe Express generated a custom event flyer, and a dynamic Quizzes app rendered interactive questions without persisting backend data. These examples highlighted how MCP servers can pull contextual data, execute actions on behalf of users, and render results via web components, including full‑screen modes and floating windows.

Key moments included Corey’s explanation that the MCP protocol is open, allowing any backend to integrate with ChatGPT, and Christine’s walkthrough of the public submission pipeline that lets creators publish apps globally. The session also emphasized the role of Codex, which can scaffold code against the Docs MCP server, dramatically shortening the traditional development cycle.

For developers and businesses, the platform lowers barriers to building AI‑enhanced services, accelerates time‑to‑market, and creates a new distribution channel within ChatGPT’s massive user base, potentially reshaping how SaaS products are delivered and monetized.

Original Description

Build a new generation of apps you can chat with right inside ChatGPT using Codex. In this Build Hour, we walkthrough how to design, build, and improve a realtime multi-player ChatGPT app from first setup to advanced UI patterns.

Corey Ching (Developer Experience) covers:

• How Apps in ChatGPT work and how to build them with Codex

• Using the Apps SDK, docs MCP server, and developer mode

• Improving an app with UI/UX guidelines

• Best practices & live Q&A

👉 OpenAI Apps SDK: https://developers.openai.com/apps-sdk

👉 What makes a great ChatGPT app: https://developers.openai.com/blog/what-makes-a-great-chatgpt-app/

👉 Follow along with the code repo: http://github.com/openai/build-hours

👉 Sign up for upcoming live Build Hours: https://webinar.openai.com/buildhours

00:00 Introduction

02:43 Apps Platform

04:07 Demo of Apps in ChatGPT

10:44 What is an App in ChatGPT

13:58 Building an App Process

16:58 Creating an App with Codex

26:57 Demo of Realtime Ping-Pong App

34:01 Best Practices: Iterating on your App

41:52 Q&A