Substack API

An unofficial Python client library for interacting with Substack newsletters and content.

Overview

This library provides Python interfaces for interacting with Substack's unofficial API, allowing you to:

• Retrieve newsletter posts, podcasts, and recommendations
• Get user profile information and subscriptions
• Fetch post content and metadata
• Search for posts within newsletters
• Access publication subscriber chats and threads
• Access paywalled content that you have written or paid for with user-provided authentication

Installation

# Using pip
pip install substack-api

# Using uv
uv add substack-api

Command-Line Interface

The library includes a CLI for quick access from the terminal. All commands output JSON by default.

# Get the 5 newest posts from a newsletter
substack newsletter posts https://example.substack.com --limit 5

# Search for posts
substack newsletter search https://example.substack.com "machine learning"

# Get metadata for a specific post
substack post metadata https://example.substack.com/p/my-post --pretty

# Look up a user's subscriptions
substack user subscriptions username

# Browse categories
substack categories
substack category newsletters --name Technology

# Run the quickstart guide for a full command reference
substack quickstart

Use --pretty for human-readable output and --cookies <path> for authenticated access to paywalled content.

Python Usage Examples

Working with Newsletters

from substack_api import Newsletter

# Initialize a newsletter by its URL
newsletter = Newsletter("https://example.substack.com")

# Get recent posts (returns Post objects)
recent_posts = newsletter.get_posts(limit=5)

# Get posts sorted by popularity
top_posts = newsletter.get_posts(sorting="top", limit=10)

# Search for posts
search_results = newsletter.search_posts("machine learning", limit=3)

# Get podcast episodes
podcasts = newsletter.get_podcasts(limit=5)

# Get recommended newsletters
recommendations = newsletter.get_recommendations()

# Get newsletter authors
authors = newsletter.get_authors()

Working with Posts

from substack_api import Post

# Initialize a post by its URL
post = Post("https://example.substack.com/p/post-slug")

# Get post metadata
metadata = post.get_metadata()

# Get the post's HTML content
content = post.get_content()

Accessing Paywalled Content with Authentication

To access paywalled content, you need to provide your own session cookies from a logged-in Substack session:

from substack_api import Newsletter, Post, SubstackAuth

# Set up authentication with your cookies
auth = SubstackAuth(cookies_path="path/to/your/cookies.json")

# Use authentication with newsletters
newsletter = Newsletter("https://example.substack.com", auth=auth)
posts = newsletter.get_posts(limit=5)  # Can now access paywalled posts

# Use authentication with individual posts
post = Post("https://example.substack.com/p/paywalled-post", auth=auth)
content = post.get_content()  # Can now access paywalled content

# Check if a post is paywalled
if post.is_paywalled():
    print("This post requires a subscription")

Getting Your Cookies

To access paywalled content, you need to export your browser cookies from a logged-in Substack session. The cookies should be in JSON format with the following structure:

[
  {
    "name": "substack.sid",
    "value": "your_session_id",
    "domain": ".substack.com",
    "path": "/",
    "secure": true
  },
  {
    "name": "substack.lli", 
    "value": "your_lli_value",
    "domain": ".substack.com",
    "path": "/",
    "secure": true
  },
  ...
]

Important: Only use your own cookies from your own authenticated session. This feature is intended for users to access their own subscribed or authored content programmatically.

Working with Users

from substack_api import User

# Initialize a user by their username
user = User("username")

# Get user profile information
profile_data = user.get_raw_data()

# Get user ID and name
user_id = user.id
name = user.name

# Get user's subscriptions
subscriptions = user.get_subscriptions()

Handling Renamed Accounts

Substack allows users to change their handle (username) at any time. When this happens, the old API endpoints return 404 errors. This library automatically handles these redirects by default.

Automatic Redirect Handling

from substack_api import User

# This will automatically follow redirects if the handle has changed
user = User("oldhandle")  # Will find the user even if they renamed to "newhandle"

# Check if a redirect occurred
if user.was_redirected:
    print(f"User was renamed from {user.original_username} to {user.username}")

Disable Redirect Following

If you prefer to handle 404s yourself:

# Disable automatic redirect following
user = User("oldhandle", follow_redirects=False)

Manual Handle Resolution

You can also manually resolve handle redirects:

from substack_api import resolve_handle_redirect

new_handle = resolve_handle_redirect("oldhandle")
if new_handle:
    print(f"Handle was renamed to: {new_handle}")

Working with Chats

Access publication subscriber chats (requires authentication):

from substack_api import Chat, SubstackAuth

# Set up authentication (required for chat access)
auth = SubstackAuth(cookies_path="cookies.json")

# Access a publication's chat using its publication ID
chat = Chat(4906951, auth=auth)

# Get recent threads
threads = chat.get_threads(limit=5)
for thread in threads:
    print(f"Thread: {thread.body[:80]}...")
    print(f"  By: {thread.author['name']} on {thread.created_at}")
    print(f"  {thread.comment_count} messages")

    # Get messages in thread
    for msg in thread.get_messages():
        print(f"    [{msg.created_at}] {msg.author['name']}: {msg.body[:60]}...")

Limitations

• This is an unofficial library and not endorsed by Substack
• APIs may change without notice, potentially breaking functionality
• Rate limiting may be enforced by Substack
• Authentication requires users to provide their own session cookies
• Users are responsible for complying with Substack's terms of service when using authentication features

Development

Running Tests

# Install dev dependencies
pip install -e ".[dev]"

# Run tests
pytest

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

1. Fork the repository
2. Create your feature branch (git checkout -b feature/amazing-feature)
3. Commit your changes (git commit -m 'Add some amazing feature')
4. Push to the branch (git push origin feature/amazing-feature)
5. Open a Pull Request

License

This project is licensed under the MIT License - see the LICENSE file for details.

Disclaimer

This package is not affiliated with, endorsed by, or connected to Substack in any way. It is an independent project created to make Substack content more accessible through Python.