OpenAI turns ChatGPT into an app platform with plug-in extensions

#What happened

At DevDay 2026, OpenAI let developers build their own app-like experiences inside ChatGPT using "plug-in extensions." Altman on stage: "With plugin extensions, you can build an editor, a dashboard, a whole workspace directly into ChatGPT and Codex." Developers get the same tools OpenAI uses internally to build ChatGPT features.

#What extensions can do

Apps get a dedicated home in the ChatGPT sidebar; interactive panels let users work with their tools while chatting; custom file viewers support each developer's file formats.

#Easier to build and find

A new Plugin Creator tool for building; a redesigned submission flow with clearer feedback; improved ranking and recommendations in the directory; plugins can be surfaced in conversations; users approve each plugin's access needs individually. Available across every ChatGPT plan.

#Sites and automations

ChatGPT Sites can host these plug-ins, letting teams share apps where each person uses their own connected data and permissions. OpenAI also added support for the proposed MCP Events spec so plug-ins can trigger automations from events in a connected app, and automations are easier to add and manage.

#Why it matters

OpenAI is turning ChatGPT into an app platform: plug-in extensions bring app-like experiences with sidebar homes, interactive panels, and file viewers directly inside ChatGPT — available on every plan.

#Source links

• TechCrunch: OpenAI expands ChatGPT's plugins with app-like interfaces and automations
• The Decoder: OpenAI reveals a new ChatGPT that looks less like a chatbot and more like an operating system

Verified 2026-09-29.