Substack Publisher API

Substackの公式Publisher APIから投稿、分析、購読者データをクエリします。

ドキュメント

substack-publisher-mcp

MCP server for Substack's official Publisher API

Note: This is an unofficial, community-developed tool and is not affiliated with, endorsed by, or supported by Substack, Inc.

The first MCP server for Substack's official Publisher API. Query post analytics, subscriber counts, and publication data directly from Claude, Cursor, or any MCP client.

Demo of substack-publisher-mcp in Claude Code

Why this server?

	substack-publisher-mcp	Other Substack MCP servers
API	Official Publisher API	Unofficial internal API
Auth	API key (stable)	Browser cookies (fragile)
Stability	Official, documented API	Breaks when Substack changes internals
Multi-publication	Built-in support	Not available

Prerequisites

Node.js 18+ — check with node --version, install from nodejs.org if missing
Substack Publisher API key — generated from your publication's Substack dashboard. If you don't see a Publisher API option there, it may not be enabled for your publication yet; see the Publisher API docs for availability.

Quick Start

1. Install

git clone https://github.com/dkships/substack-publisher-mcp.git
cd substack-publisher-mcp
npm install && npm run build

2. Configure your MCP client

Add to your client's MCP config file (create the file if it doesn't exist):

Client	Config file
Claude Desktop (macOS)	`~/Library/Application Support/Claude/claude_desktop_config.json`
Claude Desktop (Windows)	`%APPDATA%\Claude\claude_desktop_config.json`
Claude Code	`.mcp.json` in your project directory
Cursor	`.cursor/mcp.json`

{
  "mcpServers": {
    "substack": {
      "command": "node",
      "args": ["/path/to/substack-publisher-mcp/dist/index.js"],
      "env": {
        "SUBSTACK_API_KEY": "your-api-key-here"
      }
    }
  }
}

Claude Code users: Add "type": "stdio" to the server config.

Restart your MCP client after editing the config — servers load at startup.

3. Start using it

Ask Claude (or your MCP client):

"Which Substack publications do I have configured?"
"Show me my posts from the last month"
"Pull up my post with the slug my-latest-post"
"How many opens and clicks did my latest post get?"
"What are my subscriber counts for the last 30 days?"
"Look up subscriber [email protected]"

Installing through an AI agent or registry? See llms-install.md for a condensed, machine-readable setup guide.

Tools

Tool	Description	Key Parameters
`list_publications`	List configured publications	None
`list_posts`	List published posts	`startDate`, `endDate`, `sortBy`, `type`, `maxResults`, `next`
`get_post`	Get a specific post by URL slug	`urlSlug` (required)
`get_post_stats`	Get engagement stats for a post	`urlSlug` (required)
`get_subscriber_counts`	Get daily subscriber counts by type	`startDate`, `endDate`
`get_subscriber`	Look up a subscriber by email	`email` (required)

All tools except list_publications accept an optional publication parameter when multiple publications are configured.

Example responses

get_subscriber_counts

[
  {
    "date": "2025-01-15",
    "total_email_subscribers": 25000,
    "paid_subscribers": 500,
    "free_trial_subscribers": 10,
    "comp_subscribers": 50,
    "gift_subscribers": 15,
    "lifetime_subscribers": 0,
    "founding_subscribers": 25
  }
]

get_post_stats

{
  "clicks": 320,
  "opens": 5400,
  "post_id": 12345678,
  "recipients": 10000,
  "views": 6100,
  "new_free_subscriptions": 80,
  "new_paid_subscriptions": 5,
  "estimated_revenue_increase": 400
}

list_posts

{
  "posts": [
    {
      "title": "My Latest Post",
      "audience": "only_paid",
      "subtitle": "A deep dive into the topic",
      "postDate": "2025-01-15T12:00:00.000Z",
      "urlSlug": "my-latest-post",
      "coverImage": "https://substackcdn.com/image/..."
    }
  ],
  "next": "abc123cursor"
}

Multiple publications

If you manage multiple Substack publications, configure a separate API key for each using the SUBSTACK_API_KEY_<NAME> pattern:

{
  "mcpServers": {
    "substack": {
      "command": "node",
      "args": ["/path/to/substack-publisher-mcp/dist/index.js"],
      "env": {
        "SUBSTACK_API_KEY_MAIN": "your-main-blog-key",
        "SUBSTACK_API_KEY_TECH": "your-tech-newsletter-key",
        "SUBSTACK_API_KEY_COMPANY": "your-company-updates-key"
      }
    }
  }
}

Then specify which publication to query:

"Show me subscriber counts for main" "List recent posts from the tech publication"

Use list_publications to see all configured publication names.

Troubleshooting

Issue	Solution
`Unauthorized` error	Verify your API key is correct. The key goes directly in the `authorization` header with no `Bearer` prefix.
`Missing environment variables` warning	Only configure env vars for publications you have keys for. Remove the rest.
Server won't start	Make sure you ran `npm run build` after cloning. The server runs from `dist/`, not `src/`.
`No API keys configured`	Set `SUBSTACK_API_KEY` or `SUBSTACK_API_KEY_<NAME>` in your MCP client config.
Server doesn't appear in your client	Check the config file is valid JSON (no trailing commas), then restart the client.
`command not found` / `spawn node ENOENT`	Node.js isn't installed or isn't on your PATH. Check `node --version`.
Still stuck	Check your client's MCP logs. Claude Desktop on macOS: `~/Library/Logs/Claude/mcp*.log`.

API Reference

This server wraps the Substack Publisher API. See Substack's documentation for details on available data and rate limits.

Contributing

See CONTRIBUTING.md for guidelines.

License

MIT License. See LICENSE for details.

Substack is a trademark of Substack, Inc. This project is not affiliated with Substack, Inc. Use of the Substack name is for descriptive purposes only.