# Substack MCP Server
A Model Context Protocol (MCP) server for Substack integration with Claude Code and other MCP-compatible AI tools.
## Features
- **Create and manage drafts** - Create, update, and publish Substack posts programmatically
- **Image upload** - Upload images to Substack's CDN with proper metadata
- **Live blogging** - Real-time post updates with timestamps
- **Notes** - Post short-form content to Substack Notes
- **Full ProseMirror support** - Proper document structure for Substack's editor
## Installation
```bash
# Clone the repo
git clone https://github.com/acolle/substack-mcp.git
cd substack-mcp
# Install dependencies
pip install -r requirements.txt
```
## Setup
### 1. Get your Substack credentials
1. Go to your Substack dashboard in Chrome/Safari
2. Open DevTools (Cmd+Option+I or F12)
3. Go to Application tab → Cookies → your-substack.substack.com
4. Find `substack.sid` and copy its value
### 2. Create credentials file
```bash
# Create ~/.substackrc
cat > ~/.substackrc << 'EOF'
export SUBSTACK_PUBLICATION="your-publication.substack.com"
export SUBSTACK_SID="your-cookie-value-here"
EOF
```
### 3. Add to Claude Code
```bash
# Add the MCP server to Claude Code
claude mcp add substack \
--command "bash" \
--args "-c" "source ~/.substackrc && python3 $(pwd)/substack_mcp/server.py"
```
Or manually add to `~/.claude.json`:
```json
{
"mcpServers": {
"substack": {
"command": "bash",
"args": ["-c", "source ~/.substackrc && python3 /path/to/substack-mcp/substack_mcp/server.py"]
}
}
}
```
## Available Tools
| Tool | Description |
|------|-------------|
| `substack_create_draft` | Create a new draft post |
| `substack_update_draft` | Update an existing draft |
| `substack_append_to_draft` | Append content (for live blogging) |
| `substack_add_code_block` | Add a code block to a draft |
| `substack_add_image` | Add an image to a draft |
| `substack_publish` | Publish a draft |
| `substack_post_note` | Post a short note |
| `substack_get_drafts` | List all drafts |
| `substack_get_posts` | List published posts |
| `substack_live_blog_start` | Start a live blogging session |
| `substack_live_blog_end` | End live blogging session |
## Usage Examples
### Create a post with Claude Code
```
You: Create a new Substack post about AI tools
Claude: I'll create a draft for you...
[Uses substack_create_draft tool]
Created draft 12345. Edit at: https://your-pub.substack.com/publish/post/12345
```
### Upload and embed images
```
You: Add this diagram to my post [image path]
Claude: I'll upload the image and add it to your draft...
[Uses substack_add_image tool]
Image added successfully.
```
### Live blogging
```
You: Start a live blog for the product launch
Claude: Starting live blog session...
[Uses substack_live_blog_start tool]
Live blog started. I'll append updates as they happen.
```
## API Reference
### SubstackClient
The core client for interacting with Substack's API.
```python
from substack_client import SubstackClient, SubstackDocument
client = SubstackClient(token="your-sid", publication="your-pub.substack.com")
# Upload an image
img = client.upload_image("/path/to/image.png")
# Returns: {"url": "https://...", "width": 800, "height": 600, "bytes": 12345, "contentType": "image/png"}
# Create a document
doc = SubstackDocument()
doc.heading("My Post", level=2)
doc.paragraph("Hello world!")
doc.image(src=img['url'], width=img['width'], height=img['height'],
bytes_size=img['bytes'], content_type=img['contentType'])
# Create and publish
draft = client.create_draft(title="My Post", body=doc)
client.publish_draft(draft.id, send_email=False)
```
## Key Technical Details
### Image Node Structure
Substack uses ProseMirror and requires specific attributes for images:
```json
{
"type": "captionedImage",
"content": [{
"type": "image2",
"attrs": {
"src": "https://substack-post-media.s3.amazonaws.com/...",
"width": 800,
"height": 600,
"bytes": 12345,
"type": "image/png",
"internalRedirect": "https://pub.substack.com/i/{draft_id}?img={encoded_url}",
"belowTheFold": false,
"topImage": false,
"isProcessing": false
}
}]
}
```
The `internalRedirect` field is **required** - without it, Substack's editor fails to render the document.
## Credits
- Built on [Jakub Slys's Substack API reverse engineering](https://iam.slys.dev/p/no-official-api-no-problem-how-i)
- Uses [Anthropic's MCP Python SDK](https://github.com/anthropics/mcp)
## License
MIT
## Disclaimer
This uses Substack's unofficial/internal API which may change without notice. Use at your own risk.
