ChatGPT MCP and Apps: extensions you can try

OpenAI released MCP Extensions, which provides ChatGPT-specific integration points such as sidebar entries, file viewers and composer mentions, with TypeScript and Python SDKs.

The official repo offers TypeScript and Python SDKs so MCP servers can add sidebar entries, custom file viewers, composer mentions and extended forms inside ChatGPT, not just callable tools.

A Korean note walks through the MCP Extensions docs, covering sidebar, conversation panel, file viewer, /mcp and developer mode, and advises using the ui/* bridge before window.openai.

App Rings aggregates MRR, churn, trials and payouts daily while keeping historical snapshots, and supports MCP so users can ask Claude or ChatGPT for last month's MRR.

The author turned their portal into an MCP connected to Slack, letting them publish standalone pages with tools directly from Slack, Claude, and ChatGPT.

OpenAI adds ChatGPT-specific entry points and UI capabilities to MCP so third-party plugins feel like built-in features, with the repository now open source.

ChatGPT Sites hosts MCP tools through a plugin, letting assistants read data and perform defined actions, offering publishers a route beyond citations.

OpenAI lets Sites create and deploy MCP servers and package them as ChatGPT plugins that work on web, mobile, and desktop.

Upstash demonstrates a plugin extension that turns its Console into a full app inside ChatGPT and Codex, showing how MCP Apps can run this way.

A follow-up question: the Vectorize plugin page loads, and the asker wants to know whether it was built with ChatGPT Sites or a self-hosted MCP server, and how to share it between personal accounts.

Headless Hebbia is out with an API and an MCP server that map relationships like subsidiaries and past transactions, usable in ChatGPT and Claude with every claim linked to its source.

Blockworks has opened its entire data catalog through an MCP server, letting ChatGPT or Claude query prices, onchain metrics, protocol financials, disclosures, unlocks, research and news.