ChatGPT plugins (custom MCP server)

A ChatGPT plugin is a package that adds capabilities to ChatGPT and Codex. According to OpenAI, a plugin can include skills and MCP servers. With "Add custom MCP server" you can turn any remote MCP server into a plugin, so ChatGPT can use that service, for example Formify for e-signing. ChatGPT earlier called this connectors, and then apps.

Table of contents

Example H2

Share this item

How it works in Formify

In ChatGPT, open Plugins and choose Add custom MCP server.
Give it a name, for example Formify, and paste the server URL https://mcp.formify.eu/mcp.
Sign in to Formify when asked, then choose Create as a plugin.

ChatGPT can then create documents, send them for signature and check who has signed. You ask in plain language, for example "Upload this PDF and send it to the buyer and the seller." The signer gets an invitation and signs on Formify's signing page, without ChatGPT.

OpenAI describes plugins as shared between ChatGPT and Codex. Formify's MCP server also works with Codex.

Video

How to connect Formify to ChatGPT & Codex

The video shows how to connect Formify. ChatGPT has renamed these menus over time (connectors, then apps, now plugins), so the labels on screen may differ from the steps above.

FAQ

How do I add an MCP server to ChatGPT?

Open Plugins, choose Add custom MCP server, paste the server URL and sign in. Finish with Create as a plugin.

Can ChatGPT send documents for signature?

Yes, with an e-signature MCP server such as Formify's. ChatGPT prepares and sends the document, and the signer signs on Formify's signing page.

What happened to ChatGPT connectors and apps?

OpenAI renamed the feature. What used to be called connectors, and later apps, is now added as a plugin. Older guides may still use the earlier names.