OpenAI plugins & Apps SDK | Andrew Borden-Chisholm

Install

Test your own MCP server in ChatGPT

Settings → Security and login → turn on Developer mode, then chatgpt.com/plugins → plus button → enter the server's HTTPS URL.

Share a plugin repo with Codex users

codex plugin marketplace add owner/repo

The repo needs a marketplace at .agents/plugins/marketplace.json.

Publish to the public directory

Submit through platform.openai.com/plugins. Public plugins go through review.

OpenAI folded skills, connectors and the Apps SDK into one idea: a plugin. A plugin can be skills only (SKILL.md folders), an MCP server only, or both. The MCP server can also return UI, using the open MCP Apps standard plus optional ChatGPT extensions. ChatGPT and Codex share one plugin directory, so a public plugin appears in both.

When to use it

You want your product or internal tool usable from ChatGPT and Codex.
You already have a Claude Code plugin or MCP connector. OpenAI has a guide that maps each Claude plugin feature to its OpenAI equivalent, and a skills-only Claude plugin archive can be uploaded directly.
Your team needs a private catalog. Workspace admins can import and sync a GitHub marketplace.

What carries over from Claude, and what doesn’t

Carries over: skills/<name>/SKILL.md folders and remote MCP servers over Streamable HTTP.
Needs rework: commands and subagents become skills. Hooks run only in the Codex runtime, not ordinary chat. userConfig prompts aren’t supported, so credentials move to an MCP server with OAuth. Local .mcpb servers must be deployed to a public HTTPS URL.
Not supported: Claude live artifacts. Return plain content instead. Claude marketplace approvals don’t transfer.

Before you build

Only remote MCP servers are accepted for the public directory. Skills in a submission must avoid Claude-specific wording (“the model”, not “Claude”). The IDE extension doesn’t support plugins; the Codex CLI, the ChatGPT desktop app and ChatGPT web and mobile do.