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Build What’s Next on the ChatGPT Platform with Plugins | DevDay 2026

28 min videoNov 11, 2026Worth watching in full

Build an MCP plugin around one useful user task, then use extensions to add a sidebar home, contextual side panel, or interactive file viewer.

  • Add sidebar and side-panel entry points to an MCP widget; use model-context methods to share selections with ChatGPT.
  • Expose a read-only MCP search tool for @ mentions, and package an onboarding skill plus settings read/update tools.
  • Use Codex and App Plugin Creator to scaffold, test, and iterate; plugin.json-based submissions get automated checks.

The walkthroughs show plugin experiences in use and explain implementation points for extensions and events. · Best for: Developers building MCP plugins or integrating products with ChatGPT.

OpenAI presents ChatGPT plugin discovery, native extensions, MCP capabilities, and a simplified build-and-submit workflow. The talk includes demos and implementation details for developers.

Discovery and plugin growth0:25

  • Plugins can be suggested in conversations as well as found in the directory.
  • Discovery signals include post-install use, daily and weekly active usage, and retention.
  • The speaker reports 4,000 plugins in the directory and increasing plugin use.

Extensions and interactive experiences5:55

  • Plugin extensions bring interfaces into ChatGPT and Codex, including a sidebar home, side panel, composer actions, and interactive file viewers.
  • Interfaces can pass selection and other context to the conversation and model.
  • Demos include meeting notes and summaries, a 3D molecular-structure viewer, and a voice-driven Magic Path landing-page design.
  • Examples from Atlassian, Canva, and Shopify show search, content creation, analytics, and commerce workflows.

Sign-in and building with Sites16:19

  • Sign in with ChatGPT can connect a web app or plugin with ChatGPT identity; the speaker cites Supabase as an example.
  • Eligible users can bring ChatGPT token entitlements to partner tools, funded by their ChatGPT subscription.
  • Sites can host MCP servers; the speaker recommends starting with one user task and iterating with Plugin Creator.

Extension implementation20:20

  • Extensions build on MCP and MCP Apps; add entry-point configuration to open widgets in the sidebar or side panel.
  • Register supported file types to open files in an interactive widget.
  • Expose a read-only MCP tool with the required search schema for composer @ mentions.
  • Package an onboarding skill and provide settings through read and update tools.

Events and automations23:31

  • The announced MCP event support lets a server notify ChatGPT of events that can trigger automations.
  • Implement event/list to declare events and event/subscribe to receive a callback URL and signing secret; send a signed webhook when an event occurs.

Submission and getting started24:32

  • The submission form is replaced by information in plugin.json, which Codex can generate from a codebase.
  • Automated checks run on upload and provide feedback; deployed MCP server updates no longer require a new plugin submission.
  • Start in Codex with an existing repository and ask App Plugin Creator to build a first-pass plugin or add an extension home.

Step by step

  1. Choose one user task your plugin can improve.
  2. Open the project in Codex and ask App Plugin Creator to review it and implement a first-pass plugin, or add a sidebar home to an existing plugin.
  3. Configure MCP entry points for the sidebar, side panel, and any supported file types; pass relevant interface context to the conversation.
  4. Add any needed composer search tool, onboarding skill, and settings read/update tools.
  5. Test the complete user experience, then iterate; use the updated directory submission checks when ready to publish.

Tools & resources mentioned

  • App Plugin Creator — guides plugin creation and deployment.
  • Codex — work with a repository to build and iterate on a plugin.
  • Sites — host MCP servers and web apps.
  • MCP / MCP Apps — tools and widgets used as the basis for plugin extensions.
  • Sign in with ChatGPT — identity integration for web apps and plugins.
  • plugin.json — contains plugin submission information and can reference onboarding configuration.
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Notes are AI-generated from the video's transcript and may miss nuance.