How to Connect ChatGPT to Substack (2026 Guide)

ChatGPT can help with the slow parts of a newsletter: drafting from rough notes, mining your archive for ideas, and explaining your numbers. To do that well it needs your data. This guide shows how to connect ChatGPT to Substack's official MCP server if you qualify, and what to do if you don't, as of October 2026. If you use Claude instead, read how to connect Claude to Substack.

newsletterapi is an independent project, not affiliated with Substack or OpenAI. Menu names in ChatGPT change often, so check the linked OpenAI docs if a label below doesn't match what you see.

The problem

You ask ChatGPT to analyse your growth or write in your voice, and it has nothing to work from. Writers notice the gap. One wrote on X: "Substack has been annoying lately with no MCP or API/CLI support." (@ka1n0s). Another was ready to pay for the AI side of it: "Happy to pay for the LLM queries, but Substack doesn't have an API" (@davidmanheim).

Substack now has an official server for AI assistants, but it is limited to Bestseller publications, and its help article only walks through Claude. Here is the ChatGPT side, plus routes for everyone else. For background on every Substack developer surface, see our Substack API guide.

Which way of connecting ChatGPT fits me?

Your situation	Best way to connect ChatGPT	What ChatGPT gets
Admin of a Bestseller publication	Substack's official MCP server, added as a custom MCP server	Read-only stats: subscribers, revenue, retention, traffic
Publication with a Publisher API key	The open-source Publisher API server in the ChatGPT desktop app	Posts, post stats, daily subscriber counts, single-email lookup
Any writer	Your own export and RSS feed, attached to a chat or project	Your archive and subscriber data as files
You want help with Notes	Buffer's Substack integration	Scheduling of top-level Notes

A Bestseller publication is one with a Bestseller badge, which Substack awards on paid subscriber count: white for hundreds, orange for thousands, purple for tens of thousands of paid subscribers (help).

How do I connect ChatGPT to Substack's official MCP server?

Substack's help article gives the server URL, https://mcp.substack.com/api/v1/mcp, says you "can add this URL as a custom connector in any MCP-compatible client", and names ChatGPT as one. It sets two conditions: "You must be an Admin on the publication" and "Your publication must be a Bestseller publication." The server signs you in with OAuth; its discovery document lists a mcp:read scope.

The ChatGPT steps below come from OpenAI's guide to adding an MCP server in ChatGPT, which notes that "Account and workspace policies apply to adding and using custom MCP servers":

1. Open ChatGPT Plugins while signed in to ChatGPT.
2. Select the plus button, then Add custom MCP server.
3. Enter a name and description, for example "Substack stats".
4. Under Connection, enter https://mcp.substack.com/api/v1/mcp.
5. Configure authentication (Substack uses OAuth), review the risk warning, and select I understand and want to continue.
6. Select Create as a plugin, then review the tools ChatGPT discovered.
7. Install the plugin and sign in to Substack when prompted. Approve read access and, if you have several publications, pick the Bestseller one.
8. Start a new conversation, type @ in the prompt box and choose the plugin.

If you're on a Business or Enterprise workspace, OpenAI's MCP docs say "Workspace administrators can control which plugins and tools are available", so you may need an admin to allow it. If Substack shows an eligibility error, its help note says to check you're signed in to the account linked to the Bestseller publication.

What can I ask once it's connected?

Substack's own examples: "What's my current subscriber count and revenue?", "How is my paid subscriber retention trending after 6 months?", "Which traffic source drove the most views on my last post?" and "How many free subscribers have I gained since January?"

The server is read-only. It "cannot publish posts, send Notes, or modify your account", and it "cannot access profile data or Notes activity."

What if I'm not a Bestseller?

Most writers aren't. These routes don't put your account at risk.

Give ChatGPT your own export

Every writer can download "your posts, subscriber list, and related statistics" from Settings, Exports, "Create new export" (help). The Subscribers page also exports a CSV with all columns or only the visible ones (help). Attach the files you need to a chat or a project and ask your questions. Leave out readers' email addresses unless the question needs them; counts and dates answer most growth questions.

Point ChatGPT at your RSS feed

Every publication has a feed at https://your.substack.com/feed (help). It holds recent public posts, which is enough for "suggest a follow-up to my latest post". The Substack RSS feed guide explains what it includes.

Use a Publisher API key in the ChatGPT desktop app

If Substack has enabled the read-only Publisher API for your publication, the open-source substack-publisher-mcp server exposes it to AI clients. It runs as a local process, and OpenAI's MCP docs say the ChatGPT desktop app supports local STDIO servers on its Codex host: open Settings, select MCP servers, then Add server, choose STDIO, give the command from the project's README, and set your key as an environment variable. See Substack API key: Publisher API and Developer API for how to tell whether you have a key.

Get help with Notes

Buffer says Substack Notes can be created and scheduled through its app, API and MCP server (Buffer help). That covers top-level Notes only, not long-form posts.

What is ChatGPT good at for a Substack newsletter?

Job	What to give ChatGPT	Example prompt
Draft in your voice	Your posts export or a few past issues	"Using my last ten posts as a style guide, draft an issue from these notes."
Mine your archive	Posts export	"Which topics have I covered most, and what did I promise to follow up on?"
Explain your growth	Official server, Publisher API or exports	"Summarise this month: new free, new paid, and which posts drove them."
Check retention	Official server or subscriber CSV	"How has paid retention changed since spring?"
Plan Notes	Your latest post	"Give me five Notes that each pull one idea from this post."

ChatGPT can't publish long-form Substack posts through any official route. For a clean draft-then-paste workflow, see publishing to Substack from Markdown.

Should I let ChatGPT post for me?

Keep the send button for yourself. A newsletter lands in inboxes and can't be recalled. One reader put it well: "The manual-approval rule is the right center of gravity, especially with an unofficial API" (comment).

• Never give ChatGPT, or any tool, your Substack password or session. Substack's terms forbid "allowing someone else to log into Substack as you".
• Prefer read-only connections. The official server and the Publisher API are both read-only.
• Add only servers you trust. OpenAI shows a risk warning when you add a custom MCP server for a reason.

Where do I go from here?

For a comparison of the official server with open-source and hosted options, read Substack MCP server: official vs open source.

newsletterapi offers a read-only MCP server for Substack writers that works from your publication URL and your own export, with no password and no Bestseller requirement, plus a Posts API for the same archive. To get access, see pricing or email hello@newsletterapi.io.