Substack by Cotlet

dev.cotletPublished by cotlet.devOfficial publisherv1.0.2Updated Nov 7, 2026

Posts, Notes, messages, subscribers and stats for your publication.

The publisher's own server: Cotlet

Overview

AI-generated overview

Lets an assistant work inside your own Substack account: drafts, publishing, Notes, comments, subscribers, messages and stats.

What you can do
  • List, read, create, duplicate, update and delete posts and drafts, publish, schedule or cancel them
  • Read publication, daily, per-post and traffic stats, audience insights and recommendations
  • List, add, remove, tag and export subscribers, and manage post and subscriber tags
  • Read, reply to, pin, like, remove or delete comments, and read or publish Notes and replies
  • Read the home feed, search Substack, list activity and unread counts, read and send direct messages
  • Follow users, like posts and manage the publications you recommend
When to use it
Useful for writers and publishers who want an assistant to turn Markdown or notes into drafts, schedule and publish posts, answer comments, post Notes, and report subscriber, revenue and traffic numbers without leaving the chat.
Requirements
Either the hosted Cotlet endpoint, which needs a Cotlet API key sent as an Authorization bearer header, or the local PyPI package run with uvx, which needs Python 3.11 or newer and a signed-in Google Chrome session (or a pasted substack.sid cookie in SUBSTACK_AUTH_TOKEN). A Substack account is required; publisher tools work on the first publication where you are admin, owner, editor or contributor.
Before you install
Write tools act under your name and reach real people: published or scheduled posts are emailed to subscribers, and Notes, comments, replies and messages go out publicly. Deleting a post or comment is permanent, and add_subscriber triggers Substack's welcome email, so only add people who opted in. The local session file lets anyone holding it act as you, so keep it out of git and shared folders. The hosted option stores your Substack session on Cotlet's servers and is paid after a 7-day trial.

Installation

In SourceWeft

  1. Open Substack by Cotlet in the dashboard and add it to a workspace.
  2. Connect the required credentials. They are stored privately and never shown on public pages.
  3. Enable the server for the chats that should use its tools.

Web executable via Streamable HTTP. Remote servers run from the web runtime once configured in a workspace.

Use with an agent

Paste this prompt into Claude Code, Codex, Cursor or another agent — or into SourceWeft chat. The agent reads this server's install guide, shows you its publisher, endpoint and sign-in, and adds it to your client once you agree. Keys never go into a command.

Read https://sourceweft.com/mcp/dev.cotlet%2Fsubstack/install.md and connect the MCP server it describes to my client. Before changing any config, show me its publisher, endpoint and sign-in method and wait for my OK. Never put an API key in a command or in a file I would commit; ask me where it should come from.

Read the install guide the agent follows

Other MCP clients

Add this to your client's mcpServers config. The client completes OAuth sign-in on first connect.

{
  "mcpServers": {
    "substack-by-cotlet": {
      "type": "http",
      "url": "https://cotlet.dev/mcp/v1/substack/connect"
    }
  }
}

README

Substack API and MCP server: connect Substack to ChatGPT and Claude

Yes, ChatGPT, Claude and other AI agents can work in your Substack account. That includes Cursor, Codex, OpenClaw and any MCP client, plus automations in n8n, Make and Zapier. Ask in plain words, and the AI drafts posts from your notes, schedules them, posts Notes, answers comments and reports your subscriber and post stats. It shows you what it will do first and sends nothing to other people until you say so.

As of November 2026, this repo is the missing piece: 50 Substack tools for AI assistants and scripts.

What you can ask

Turn essay.md into a draft for everyone and schedule it for Tuesday 8:00 New York time. Once it is out, post a Note with a link card to it.

Find comments on my last three posts that I have not answered and draft a short reply to each.

Last week's numbers: new and paid subscribers, cancellations, revenue, and opens for each post.

Where did my readers come from in the last 30 days?

Two ways to get it

Ready to use, at CotletRun it yourself, this repo
Forwriters and publishersdevelopers
Setupsign in to Substack once, about 5 minutes, nothing to installPython and a terminal
Works inChatGPT and Claude apps, on your phone too, Cursor, Codex, OpenClaw, any MCP client, n8n, Make, Zapier, REST APIClaude Code, Claude Desktop, Cursor, Codex on your computer
Runs24/7, your computer can be offwhile your computer is on
Price7 days free, no cardfree

Cotlet is best for writers and publishers who want ChatGPT, Claude or another AI agent to work in Substack for them, with nothing to install.

Start free at cotlet.dev →

Run it yourself

A Substack API and a Substack MCP server you run on your own computer, in Python, on the session of your own Google Chrome. All 50 Substack tools we run in production at Cotlet: posts and drafts from Markdown, publishing and scheduling, Notes, comments, subscribers, stats, recommendations and direct messages.

Substack has no public API to write posts, publish Notes or manage subscribers, and no official MCP server. This repo gives you both:

  • MCP server for Claude Code, Claude Desktop, Cursor, Codex and any MCP client, over stdio or HTTP. Setup
  • REST API on http://127.0.0.1:8787/api/v1/substack, with OpenAPI docs at /docs. Setup
  • Python: call("list_posts", status="draft"), plus 14 ready scripts in examples/.

Free for your own use, your own business included (license).

[Substack MCP server] [Python 3.11+] [License: Elastic 2.0] [MCP Badge]

bash
uv tool install substack-api-mcp                  # or: pip install substack-api-mcpsubstack-mcp connect                               # reads your Substack session from Chromesubstack-mcp call list_postsclaude mcp add substack -- uvx substack-api-mcp mcp

Contents

Questions from Substack users

Does Substack have an API? Only a limited one (checked 11 Oct 2026). Its Developer API looks up public creator profiles after approval, and there is no public API to write posts or Notes, manage subscribers or send email. RSS reads public posts only. This repo and Cotlet give you 50 Substack tools as a REST API and an MCP server.

Can I get a Substack API key? Not from Substack for your own account. With Cotlet you get your own API key that works with your Substack account, for scripts, n8n, Make, Zapier or any HTTP client. This repo needs no key: it runs on your computer, on your own Substack session.

Is there an official ChatGPT integration for Substack? Partly. Substack has an official Claude connector that reads your publication's data, such as subscribers, revenue and post stats. It cannot write. Cotlet adds the writing side: drafts, publishing and scheduling, Notes, comments and messages, in ChatGPT, Claude and other AI agents.

How do I connect Substack to ChatGPT? Sign up at cotlet.dev, sign in to Substack once in your Cloud Browser there, and add Cotlet to ChatGPT, following the steps in your account. Then ask ChatGPT about your Substack like you would ask an assistant. ChatGPT needs a server on the internet, so this repo alone, running on your computer, does not connect to ChatGPT.

Can ChatGPT write and schedule my Substack posts? Yes, with Cotlet. It turns your notes or a Markdown file into a Substack draft, shows it to you and publishes or schedules it after your OK. It can post a Note about it once it is out.

Can ChatGPT read my Substack stats? Yes, with Cotlet: new and paid subscribers, cancellations, revenue, opens per post and where your readers came from, in plain words.

Can I automate Substack with Zapier, Make or n8n? Substack has no official way to write posts from Zapier, Make or n8n. With Cotlet they can create drafts, publish posts and post Notes, for example from a Google Doc or an RSS feed.

Can I use it from my phone? Yes, with Cotlet: once it is set up, the ChatGPT and Claude apps on your phone can use Substack for you.

Do I need to be technical? For Cotlet, no: you sign in to Substack and add Cotlet to ChatGPT or Claude, with step-by-step instructions in your account. This repo is for people who are fine with Python and a terminal.

Is my Substack account safe? Yes. Neither Cotlet nor this repo sees or stores your Substack password. You sign in yourself, the way you always do, and the AI works on that signed-in session. Anything that reaches other people asks for your OK first: in Cotlet by default, here through your MCP client.

Is it free? This repo is free, also in your own business. Cotlet is free for 7 days with no card, then one-time credit packs from $29, no subscription. Pricing.

I manage Substack for several accounts or clients. Does that work? Yes, with Cotlet. Each Substack login gets its own connection. Write to [email protected] and tell us how many accounts you manage.

How it works

text
AI agent (MCP) / script (REST, Python) ──▶ substack-mcp on your computer ──your Substack cookies──▶ substack.com                                                     ▲                         substack-mcp connect ───────┘ reads them once from your Chrome (DevTools Protocol)
  1. You sign in to Substack in your own Chrome, the way you always do.
  2. substack-mcp connect attaches to that Chrome through the Chrome DevTools Protocol, reads the substack.com cookies and saves them to ~/.config/substack-api-mcp/session.json, readable by your user only. Substack signs in by an emailed code or link, so there is no password to see or store.
  3. Every tool call is a request to Substack's own web app endpoints (substack.com/api/v1 for the reader side, yourname.substack.com/api/v1 for your publication's dashboard) with those cookies, sent with curl_cffi, which copies Chrome's TLS fingerprint. No headless browser runs.

Substack's session cookie (substack.sid) lasts about three months. When Substack signs you out, the server reads the cookies from Chrome again, if Chrome is open with remote debugging on.

Requirements

  • Python 3.11 or newer.
  • Google Chrome 144 or newer, signed in to Substack. Any Chrome or Chromium works with a debugging port.
  • macOS, Linux or Windows.
  • A Substack account. Publisher tools (posts, subscribers, stats, comments) work on the first publication your account runs as admin, owner, editor or contributor. Reader tools (feed, search, Notes, messages) work on any account.

Install

From PyPI:

bash
uv tool install substack-api-mcp       # or: pipx install substack-api-mcp, or: pip install substack-api-mcpsubstack-mcp --version

MCP clients can also run it with no install: uvx substack-api-mcp mcp.

From source:

bash
git clone https://github.com/cotletdev/substack-api-mcp-server.gitcd substack-api-mcp-serverpython3 -m venv .venv. .venv/bin/activate              # Windows: .venv\Scripts\activatepip install -e .substack-mcp --version

With uv: uv venv && uv pip install -e ., then uv run substack-mcp ....

Setting it up with an AI agent (Claude Code, Codex, Cursor)? Open it in this folder and ask it to set up the repo: AGENTS.md tells it every step, and it asks you only for the steps in Chrome.

To update: uv tool upgrade substack-api-mcp (or pip install -U substack-api-mcp), from source git pull && pip install -e .. We copy every change of the hosted Substack tools into this repo.

Connect your Chrome

Option A: your everyday Chrome (recommended)

  1. Open chrome://inspect/#remote-debugging in Chrome and switch remote debugging on. Chrome then accepts DevTools connections from programs on this computer, and asks you before each one.

  2. Make sure you are signed in at substack.com.

  3. Run:

    bash
    substack-mcp connect
  4. Chrome asks whether to allow the connection. Click Allow.

text
Saved 19 Substack cookies to /Users/you/.config/substack-api-mcp/session.jsonSigned in to Substack as Maya Chen (@mayachen)

You can switch remote debugging off again afterwards. Leave it on if you want the server to pick up a new session by itself after Substack signs you out.

connect looks for Chrome's DevToolsActivePort file in the default profile folder. For Chrome Beta, Canary or a custom profile folder, pass --profile-dir "<folder>".

Option B: a Chrome with a debugging port

Chrome does not open a debugging port on your default profile, so start a separate one, sign in to Substack there once, and connect to it:

bash
# macOS"/Applications/Google Chrome.app/Contents/MacOS/Google Chrome" --remote-debugging-port=9222 --user-data-dir="$HOME/.chrome-substack"# Linuxgoogle-chrome --remote-debugging-port=9222 --user-data-dir="$HOME/.chrome-substack"# Windows"C:\Program Files\Google\Chrome\Application\chrome.exe" --remote-debugging-port=9222 --user-data-dir="%USERPROFILE%\.chrome-substack"
substack-mcp connect --cdp http://127.0.0.1:9222

--cdp also takes a ws:// DevTools URL, for example of a Chrome on another machine reached over an SSH tunnel.

Option C: paste the cookie by hand

For a server with no Chrome: in Chrome open DevTools on substack.com, Application > Cookies > https://substack.com, copy the value of substack.sid, then:

bash
substack-mcp connect --token          # paste it, input is hidden# or, without a session file:export SUBSTACK_AUTH_TOKEN=...

A pasted token is not refreshed on its own. Paste a new one when Substack signs you out.

Check the session at any time:

bash
substack-mcp status

MCP server

The MCP server lists every tool with its input schema, a description written for agents, and hints: read tools are marked read-only, and tools that publish, message or delete are marked so your client asks before running them.

Claude Code

bash
claude mcp add substack -- uvx substack-api-mcp mcp# read only:claude mcp add substack -- uvx substack-api-mcp mcp --read-only

Claude Desktop

~/Library/Application Support/Claude/claude_desktop_config.json (macOS) or %APPDATA%\Claude\claude_desktop_config.json (Windows):

json
{  "mcpServers": {    "substack": {      "command": "uvx",      "args": ["substack-api-mcp", "mcp"]    }  }}

Cursor

~/.cursor/mcp.json, the same block as Claude Desktop. A ready copy is in mcp.json.

Codex

~/.codex/config.toml:

toml
[mcp_servers.substack]command = "uvx"args = ["substack-api-mcp", "mcp"]

Over HTTP

substack-mcp serve also serves MCP over streamable HTTP at http://127.0.0.1:8787/mcp, for clients that take a URL:

bash
substack-mcp serveclaude mcp add --transport http substack http://127.0.0.1:8787/mcp

Then ask your agent things like:

Turn essay.md into a draft for everyone and schedule it for Tuesday 8:00 New York time. Once it is out, post a Note with a link card to it.

Find comments on my last three posts that I have not answered and draft a short reply to each.

Last week's numbers: new and paid subscribers, cancellations, revenue, and opens for each post.

Where did my readers come from in the last 30 days?

REST API

bash
substack-mcp serve                    # http://127.0.0.1:8787, MCP at /mcp, docs at /docs

Each tool has its own route under /api/v1/substack, the same paths as the hosted API at cotlet.dev, so code written against one works with the other. Path parts and the query string are arguments, and a JSON body adds the rest.

bash
curl 'http://127.0.0.1:8787/api/v1/substack/posts?status=scheduled'curl 'http://127.0.0.1:8787/api/v1/substack/stats?period=30d'curl -X POST http://127.0.0.1:8787/api/v1/substack/drafts \  -H 'Content-Type: application/json' \  -d '{"title": "Notes on pricing", "body_markdown": "## Why I raised prices\n\nThree reasons..."}'

Any tool by name, body as its arguments:

bash
curl -X POST http://127.0.0.1:8787/api/v1/substack/tools/list_comments -d '{"post_id": "148213977"}'
  • GET /api/v1/substack/tools: every tool with its route, input schema and an example answer.
  • GET /docs: interactive OpenAPI docs, GET /openapi.json the schema, for n8n, Postman or a generated client.
  • Answers are JSON. Lists return next_cursor; pass it back as cursor for the next page.

The server listens on 127.0.0.1 only. To reach it from another device of yours, set a token, and every request then needs Authorization: Bearer <token>:

bash
SUBSTACK_MCP_TOKEN=$(openssl rand -hex 24) substack-mcp serve --host 0.0.0.0

Python and the example scripts

Straight from Python, no server needed:

python
from substack_api_mcp import callfrom substack_api_mcp.scripting import paginate, write_rows
posts = list(paginate("list_posts", {"status": "published"}, "posts"))write_rows(posts, "posts.csv")draft = call("create_draft", title="Notes on pricing", body_markdown="Three reasons...")call("schedule_post", post_id=draft["post_id"], publish_at="2026-11-03T08:00:00-05:00")

Or one tool from the shell: substack-mcp call get_post_stats post_id=148213977, or with a JSON object.

Ready scripts in examples/. Each prints JSON, takes --out file.csv or --out file.json where it makes sense, and --help:

ScriptWhat it does
draft_from_markdown.pyA .md file to a draft: the first heading is the title, headings, links and lists are kept. --publish-at schedules it.
schedule_post.pySchedules a draft for a set time, or --cancel takes it back to drafts.
publish_note.pyA Note now or at a set time, --link-latest adds a link card to your newest post.
list_posts.pyPublished, draft or scheduled posts: title, audience, dates, URL.
get_post.pyOne post saved as a Markdown file.
weekly_report.pyNew and paid subscribers, cancellations, revenue, and each new post's opens and new subscribers.
post_stats.pyOpens, open rate, views, likes, restacks and new subscribers for your last N posts.
daily_stats.pySubscribers, paid subscribers, followers and views day by day.
traffic_sources.pyWhere your visitors came from, most views first.
unanswered_comments.pyComments on your last N posts that you have not replied to.
reply_to_comment.pyA reply under one comment.
list_subscribers.pySubscribers by plan or join date, with activity rating.
export_subscribers.pyThe full list as the CSV that Export gives in the dashboard.
add_subscribers.pyAdds emails from a text or CSV file as free subscribers, after asking you.
bash
python examples/draft_from_markdown.py essay.md --publish-at 2026-11-03T08:00:00-05:00python examples/unanswered_comments.py --last 3 --out todo.csv

On a schedule, cron on your own computer works while it is on: 0 8 * * 1 cd ~/substack-api-mcp-server && .venv/bin/python examples/weekly_report.py.

All 50 tools

post_id comes from list_posts, comment_id from list_comments. substack-mcp tools prints this list, substack-mcp tools --json adds the input schemas.

Posts and drafts

ToolAccessREST routeWhat it does
list_postsreadGET /postsPosts of your publication, newest first, with status and audience.
get_postreadGET /posts/{post_id}Full post: title, subtitle, body as Markdown, audience, URL and dates.
create_draftwritePOST /draftsNew draft from Markdown. Nothing is sent until you publish or schedule it.
update_draftwritePATCH /drafts/{post_id}Change the title, subtitle, body or audience of a draft.
duplicate_postwritePOST /posts/{post_id}/duplicateCopy any post into a new draft.
delete_postwriteDELETE /posts/{post_id}Delete a draft, scheduled or published post, with its comments.

Publishing

ToolAccessREST routeWhat it does
publish_postwritePOST /posts/{post_id}/publishPublish a draft now.
schedule_postwritePUT /posts/{post_id}/schedulePublish a draft at a set time, on the web and by email.
cancel_scheduled_postwriteDELETE /posts/{post_id}/scheduleStop a scheduled post from going out; it stays as a draft.
unpublish_postwriteDELETE /posts/{post_id}/publishTake a published post off the web and back to drafts.

Sections and post tags

ToolAccessREST routeWhat it does
list_sectionsreadGET /sectionsSections of your publication, the separate newsletters inside it.
list_post_tagsreadGET /post-tagsTags your publication uses to group posts.
create_post_tagwritePOST /post-tagsNew tag for grouping your posts.
tag_postwritePUT /posts/{post_id}/tags/{tag_id}Add a tag to a post, or take it off.

Comments

ToolAccessREST routeWhat it does
list_commentsreadGET /posts/{post_id}/commentsComments on a post, with author, text and whether you replied.
reply_to_commentwritePOST /comments/{comment_id}/repliesReply as you under a comment on your post.
pin_commentwritePUT /comments/{comment_id}/pinPin a comment to the top of your post's comments, or unpin it.
like_commentwritePUT /comments/{comment_id}/likeLike or unlike a comment or a Note as you.
remove_commentwritePOST /comments/{comment_id}/removeRemove someone's comment from your post as the publication's moderator.
delete_commentwriteDELETE /comments/{comment_id}Delete one of your own comments, Notes or Note replies.

Notes

ToolAccessREST routeWhat it does
list_notesreadGET /notesNotes posted by you or any other Substack user, newest first, with likes and replies.
list_note_repliesreadGET /notes/{note_id}/repliesReplies under a Note, with author, text and likes.
publish_notewritePOST /notesShort post in Substack Notes, now or at a set time, optionally with a link card to one of your posts.
reply_to_notewritePOST /notes/{note_id}/repliesReply as you under any Note or Note reply.

Subscribers

ToolAccessREST routeWhat it does
list_subscribersreadGET /subscribersSubscribers with plan, start date and activity rating.
add_subscriberwritePOST /subscribersAdd one email to your list as a free subscriber.
remove_subscriberwriteDELETE /subscribers/{email}Remove one email from your subscriber list.
export_subscribersreadGET /subscribers/exportThe full subscriber list as a CSV download link, with the row count.
list_subscriber_tagsreadGET /subscriber-tagsTags you use to group subscribers.
create_subscriber_tagwritePOST /subscriber-tagsNew private tag for grouping subscribers.
tag_subscriberswritePOST /subscriber-tags/{tag_id}/subscribersPut a tag on subscribers by email, or take it off.

Stats

ToolAccessREST routeWhat it does
get_publication_statsreadGET /statsTotal and paid subscribers, new subscribers, paid cancellations and estimated revenue for a period.
get_daily_statsreadGET /stats/dailyDay by day: total and paid subscribers, followers and views.
get_audience_insightsreadGET /audienceWhere your subscribers live, and which publications share your readers.
list_traffic_sourcesreadGET /traffic-sourcesWhere your publication's visitors came from in a period, most views first.
get_post_statsreadGET /posts/{post_id}/statsRecipients, opens, open rate, views, likes, restacks and subscribers gained.
get_post_trafficreadGET /posts/{post_id}/trafficWhere a post's readers came from: sources, categories and devices.
get_post_engagementreadGET /posts/{post_id}/engagementWho liked and commented on a post, and the subscribers it won and lost.

Recommendations

ToolAccessREST routeWhat it does
list_recommendationsreadGET /recommendationsPublications you recommend, or that recommend you, with the subscribers each sent.
recommend_publicationwritePUT /recommendations/{publication_id}Recommend another publication to your readers, or stop recommending it.

Reader, feed and messages

ToolAccessREST routeWhat it does
get_feedreadGET /feedYour Substack home feed: posts and Notes, For you or Following.
search_substackreadGET /searchSearch all of Substack for people, posts and Notes.
list_activityreadGET /activityYour Substack notifications: replies, likes, new followers, restacks, newest first.
get_unread_countsreadGET /unread-countsHow many unread direct messages, message requests and activity notifications you have.
list_conversationsreadGET /conversationsYour direct-message conversations, latest first, with the last message.
get_conversationreadGET /conversations/{conversation_id}The latest messages of one direct-message conversation, oldest first.
send_messagewritePOST /messagesSend a direct message on Substack, in a conversation or to a person.
follow_userwritePUT /users/{user}/followFollow or unfollow a Substack user, so their Notes reach your feed.
like_postwritePUT /posts/{post_id}/likeLike or unlike any Substack post as you.
list_subscriptionsreadGET /subscriptionsPublications you subscribe to, with your plan and whether their emails reach you.

Never built, on purpose: your Substack sign-in, email, profile and account settings, your publication's address or ownership, and anything that moves money (paid plans, payouts, comps). Every request passes a guard that refuses writes to those Substack paths.

Configuration

VariableDefaultWhat it does
SUBSTACK_MCP_HOME~/.config/substack-api-mcpFolder of session.json.
SUBSTACK_AUTH_TOKENSubstack substack.sid cookie, instead of substack-mcp connect.
SUBSTACK_PROXYProxy for every request to Substack, e.g. http://user:pass@host:port.
SUBSTACK_MCP_READ_ONLY1 hides and refuses every tool that changes Substack (same as --read-only).
SUBSTACK_MCP_TOKENBearer token required by serve; needed to listen beyond 127.0.0.1.
SUBSTACK_MCP_HOST, SUBSTACK_MCP_PORT127.0.0.1, 8787Address of serve.

Security and your Substack account

  • No password anywhere. Substack signs in by an emailed code. Only cookies are read, and only those of substack.com.
  • The session file is yours. session.json is created with mode 0600. Anyone who has it can act as you on Substack, so keep it out of git and shared folders.
  • Local by default. serve binds to 127.0.0.1 and refuses another address without SUBSTACK_MCP_TOKEN.
  • substack.com only. Requests and redirects outside substack.com and its subdomains are refused.
  • Read-only mode. --read-only or SUBSTACK_MCP_READ_ONLY=1 exposes the 25 read tools only.
  • Actions reach real people. Published and scheduled posts are emailed to your subscribers, and Notes, comments, replies and DMs go out under your name. MCP clients ask before running them; a script does not, so try it on a test publication first.
  • Add only people who asked. add_subscriber sends Substack's welcome email. Importing people who did not sign up breaks Substack's rules.

Errors

The REST API answers {"error": "<code>", "message": "..."}. The MCP server returns the same code and message as a tool error.

StatusCodeWhat to do
401auth_required, auth_expiredNo session, Substack signed you out, or it asks you to sign in again before a sensitive action (subscriber lists). Sign out and in at substack.com in Chrome, then run substack-mcp connect.
403app_permission_deniedYour role in the publication cannot do this.
403scope_deniedThe server runs read-only, or the call would change your account settings.
403target_blockedSubstack refused the request or showed a bot check. Open substack.com in Chrome once, then retry.
409captcha_requiredSubstack asks for a CAPTCHA. Solve it in Chrome.
422invalid_inputAn argument is missing or wrong; the message names it.
429rate_limitedSubstack is limiting the account. Wait a few minutes.
502target_errorSubstack answered with an error, or changed its site. git pull for the latest tools, or open an issue.

Self-hosted or hosted

This repoCotlet, hosted
Toolsthe same 50the same 50
Runson your computer, while it is onin the cloud, 24/7
Substack sessionyour Chrome, cookies in a local fileyour own Cloud Browser in the EU, profile encrypted with AES-256-GCM
When Substack changes its sitegit pull once we have fixed itfixed for you, every tool tested daily
Approvalsyour MCP client asks per callposts, Notes, replies and DMs wait for your OK, switchable per tool
Works withMCP clients on your machine, local scriptsClaude.ai and ChatGPT connectors, n8n, Make, Zapier, any HTTP client
Who may use ityou and your own businessyou, teams, businesses, agencies
Pricefreefree 7-day trial with 2,000 credits, no card; then one-time packs from $29 for 5,000 credits

On the hosted version a successful call uses 10 credits for most tools, failed calls are free, and the Cloud Browser uses 50 credits a day while it has an app enabled for agents. Full pricing.

FAQ

Is there a Substack MCP server for Claude, ChatGPT or Cursor? Yes, this one runs on your machine: substack-mcp mcp for Claude Code, Claude Desktop, Cursor and Codex. ChatGPT and Claude.ai connectors need a public HTTPS URL, which the hosted Substack MCP server gives you.

Can I schedule Substack posts from Markdown? Yes: python examples/draft_from_markdown.py essay.md --publish-at 2026-11-03T08:00:00-05:00. The Substack editor does not import Markdown. The script sends the file as a draft with its headings, bold text, links, lists and code blocks, then schedules it. Images have to be public URLs.

Can it schedule Notes as well as posts? Yes. publish_note takes a publish_at time and the Note waits in your scheduled Notes until then. A link card needs a published post.

Can I export my Substack subscribers to CSV? Yes: python examples/export_subscribers.py --out subscribers.csv gives the same CSV as Export in the subscriber dashboard. list_subscribers.py --plan paid or --since 2026-10-01 gives a filtered list with plan, join date and activity rating.

Can I export my posts as Markdown? Yes, one at a time with examples/get_post.py --post-id <id> --out post.md, including the paywalled part and drafts of your own publication. list_posts.py gives the IDs.

Is this a Substack scraper? It does what people want a scraper for (export posts, subscribers and stats) but does not parse HTML in a headless browser. It calls the same JSON endpoints the Substack web app calls, in your own account and publication.

Why does it need my Chrome? To read your Substack session. Substack signs in by an emailed code, so there is no password to give it anyway. Chrome is used once per sign-in, not for each call.

What happens when Substack signs me out? Calls fail with auth_expired. With Chrome remote debugging on, the server reads the new cookies on the next call (click Allow when Chrome asks); otherwise run substack-mcp connect again. Subscriber lists sometimes ask for a fresh sign-in even with a valid session: sign out and in again at substack.com, then connect.

Does it need a paid Substack plan? No. Revenue, paid subscribers and cancellations exist only for publications with paid subscriptions.

Can it email all my subscribers? Only by publishing or scheduling a post, the way the editor sends it. Substack emails a post once; edits after the send show on the web and in the app.

Can it run on a VPS or in Docker? Technically yes, with SUBSTACK_AUTH_TOKEN. Substack then sees your session from a datacenter IP, which looks less like you. For an always-on setup the hosted version keeps your session in your own Cloud Browser on a fixed IP.

Will my Substack account get banned? Requests carry Chrome's fingerprint and go out one at a time, as you would click. Nobody can promise a platform never acts. Keep to your normal use and do not add or message people in bulk.

Can I use it at work or for my clients? At work and in your own business, yes, free. You may not offer it to others as a hosted or managed service. For client work, use Cotlet or write to [email protected].

Is it open source? The source is public under the Elastic License 2.0: free to use and change, also in your own business, but not to resell as a hosted service.

A tool broke or I need another one. Open an issue with the tool name and the error message.

License

Elastic License 2.0. In short:

  • Allowed: using it for yourself and in your own business, free. Changing the code and sharing it under the same license.
  • Not allowed: offering it to others as a hosted or managed service, removing the license notices, getting around its limits.

Earlier versions of this repo (the scripts for the hosted API, up to commit 4399e88) stay MIT.


[Cotlet]

Maintained by Cotlet (@cotletdev). Substack is a trademark of its owner. This project is unofficial and not affiliated with, endorsed or sponsored by Substack.

Source: README.md at commit feaf7ea

Tools

50

add_subscriber

Add subscriber

Add one email to your list as a free subscriber. Adds one email as a free subscriber, the same as Add subscribers in the dashboard, and Substack sends its usual welcome email. Substack adds the email in the background, so list_subscribers may show it a minute later. Add only people who agreed to hear from you.

Parametersemailrequired

cancel_scheduled_post

Cancel scheduled post

Stop a scheduled post from going out; it stays as a draft. Removes the scheduled time from a post, so nothing is published or emailed then; the post stays a draft with its content. Schedule it again with schedule_post. A post with no schedule returns an error.

Parameterspost_idrequired

create_draft

Create draft

New draft from Markdown. Nothing is sent until you publish or schedule it. Creates a draft in your publication and returns its post_id and editor link. Markdown covers headings, paragraphs, bullet and numbered lists, quotes, code blocks, rules, images by public URL, bold, italic, strikethrough, inline code and links; local image files cannot be used. Sending is a separate step: schedule_post or publish_post. A draft reaches no one, so it runs without asking.

Parameterstitlerequiredaudiencesubtitlebody_markdownrequired

create_post_tag

Create post tag

New tag for grouping your posts. Creates a post tag on your publication; Substack makes the slug from the name. A tag with no posts shows nowhere. Put posts under it with tag_post.

Parametersnamerequired

create_subscriber_tag

Create subscriber tag

New private tag for grouping subscribers. Creates a subscriber tag on your publication. Tags are private: subscribers never see them. Put subscribers under it with tag_subscribers.

Parametersnamerequired

delete_comment

Delete comment or Note

Delete one of your own comments, Notes or Note replies. Deletes something you wrote: a comment under a post, a Note or a reply to a Note. Replies other people wrote under it stay, under a deleted placeholder. Someone else's comment returns an error; on your own posts remove it with remove_comment.

Parameterscomment_idrequired

delete_post

Delete post

Delete a draft, scheduled or published post, with its comments. Deletes one post of your publication for good: a draft, a scheduled post (its send is cancelled) or a published post, which leaves the web, the archive and the app with its comments and stats. Emails already sent stay in inboxes. Substack has no undo; unpublish_post keeps the post as a draft instead.

Parameterspost_idrequired

duplicate_post

Duplicate post

Copy any post into a new draft. Makes a new draft with the title, subtitle, body and settings of a draft or published post, as Duplicate in the post list does. Substack puts [COPY] in front of the title; change it with update_draft. Nothing is published or sent.

Parameterspost_idrequired

export_subscribers

Export subscribers

The full subscriber list as a CSV download link, with the row count. Builds the same CSV as Export in the subscriber dashboard: email, name, subscription type, activity rating and start date. Substack builds the file in the background; the call waits up to about a minute and otherwise asks you to try again later. The link needs no sign-in and works until expires_at, 24 hours when we recorded it. For filtered pages use list_subscribers.

Takes no parameters.

follow_user

Follow user

Follow or unfollow a Substack user, so their Notes reach your feed. Follows a person on Substack, as Follow on their profile does, or unfollows them. Following is not subscribing: you get their Notes and activity in the app, not their newsletter by email. They see the follow.

Parametersuserrequiredunfollow

get_audience_insights

Get audience insights

Where your subscribers live, and which publications share your readers. Returns Analytics > Statistics > Audience: subscriber counts per country (region world, ISO codes such as us, gb) or per US state (region usa, codes such as ny, ca), all subscribers or paid only, the number of countries and states with any subscriber, and the publications whose readers overlap most with yours. Substack computes these in the background; a new publication has empty lists for a while.

Parametersregionpaid_only

get_conversation

Get conversation

The latest messages of one direct-message conversation, oldest first. Returns who is in the conversation and its latest messages as the chat window first shows them, oldest first, with sender, text and time. Opening a conversation this way marks nothing read.

Parametersconversation_idrequired

get_daily_stats

Get daily stats

Day by day: total and paid subscribers, followers and views. Returns one row per day of the period, as the charts on the dashboard home and in Audience: total subscribers, paid subscribers and followers at the end of the day, and the day's views across your site and the app. Days Substack has no number for are null; a young publication starts on the day it was made.

Parametersperiod

get_feed

Get feed

Your Substack home feed: posts and Notes, For you or Following. Returns one page of the home feed of the Substack app, split into posts and Notes in feed order. for_you is Substack's own mix; following holds only people and publications you follow or subscribe to. Suggestions of people to follow are left out. Reading marks nothing seen. Page with next_cursor; the feed is personal and changes between calls.

Parameterstabcursor

get_post

Get post

Full post: title, subtitle, body as Markdown, audience, URL and dates. Returns one post of your publication, draft, scheduled or published, with its full body as Markdown, including the paywalled part. Images come back as URLs. Buttons, embeds and footnotes come back as plain text, so writing the body back with update_draft drops them. A scheduled post also has publish_at.

Parameterspost_idrequired

get_post_engagement

Get post engagement

Who liked and commented on a post, and the subscribers it won and lost. Returns the Engagement and Growth parts of a post's stats: like and comment counts with the people behind them (name and handle, never email), and the free signups, paid subscriptions and unsubscribes Substack credits to the post. Counts keep changing for days after a send.

Parameterspost_idrequired

get_post_stats

Get post stats

Recipients, opens, open rate, views, likes, restacks and subscribers gained. Returns the engagement numbers of one published post, as on its stats page in the dashboard. Email numbers cover the send; views include the web; likes are reactions. A draft or scheduled post returns an error. Numbers keep growing for days after a send, so check again later.

Parameterspost_idrequired

get_post_traffic

Get post traffic

Where a post's readers came from: sources, categories and devices. Returns the Traffic part of a post's stats: each source (app, email, a website, search) with its views, share of all views and the free and paid subscribers it brought, the share per source category and per device. A post nobody has read yet returns empty lists.

Parameterspost_idrequired

get_publication_stats

Get publication stats

Total and paid subscribers, new subscribers, paid cancellations and estimated revenue for a period. Totals are from the publisher dashboard at the end of the period (7, 30 or 90 days). subscribers_churned counts paid cancellations only; Substack keeps no count of free unsubscribes. subscribers_new is the growth in total subscribers plus those cancellations. revenue_usd is not money received: it is the dashboard's annualized revenue at the end of the period, times the period's share of a year.

Parametersperiod

get_unread_counts

Get unread counts

How many unread direct messages, message requests and activity notifications you have. Returns the badges of the Substack app: unread direct messages, pending message requests and unread activity (likes, replies, new followers, restacks). Reading them marks nothing read.

Takes no parameters.

like_comment

Like comment or Note

Like or unlike a comment or a Note as you. Adds your heart to any Note or Note reply, or to a comment under a post of your publication, or removes it with unlike. Comments and Notes share one ID space, so a Note ID from list_notes or search_substack works too. The author sees your like in their activity.

Parametersunlikecomment_idrequired

like_post

Like post

Like or unlike any Substack post as you. Adds your heart to a post on any publication, as the heart under a post does, or removes it with unlike. The author sees your like in their activity. Liking twice keeps one like.

Parametersunlikepost_idrequired

list_activity

List activity

Your Substack notifications: replies, likes, new followers, restacks, newest first. Returns the Activity tab of the Substack app, newest first. type is Substack's own name, e.g. note_reply, note_like, comment_reply, comment_like, post_like, follow, restack or mention. from lists the latest people behind a grouped item and people counts all of them. A reply or mention carries its comment_id and text; on_comment_id and on_post_id point at what it was about. Reading the list marks nothing read. Page with next_cursor.

Parameterscursorfilter

list_comments

List comments

Comments on a post, with author, text and whether you replied. Returns all comments of one post at once, oldest first, with replies nested under their parent. Deleted comments are left out. replied is true when you answered anywhere in the thread under the comment; unanswered_only keeps only top-level comments where you did not. Pass comment_id to reply_to_comment.

Parameterspost_idrequiredunanswered_only

list_conversations

List conversations

Your direct-message conversations, latest first, with the last message. Returns your Substack chat inbox: one-to-one and group direct messages with who they are with, the last message, its time, your unread count and whether it is a message request from someone you do not follow. Publication chats are left out. Reading the list does not mark anything read. Pass conversation_id to get_conversation or send_message.

Parameterscursorunread_only

list_note_replies

List Note replies

Replies under a Note, with author, text and likes. Returns the direct replies under one Note (yours or anyone's), in Substack's order. replies is the count under each reply; list those by passing its note_id. Substack sends no handle with replies, so author.handle is empty and url is null. Page with next_cursor.

Parameterscursornote_idrequired

list_notes

List Notes

Notes posted by you or any other Substack user, newest first, with likes and replies. Returns the Notes on a profile's Notes tab, newest first: text, time, likes, restacks, reply count and link. Without user it lists yours. Posts and restacks of posts on the profile are left out. Page with next_cursor. Pass note_id to list_note_replies, like_comment or reply_to_note.

Parametersusercursor

list_post_tags

List post tags

Tags your publication uses to group posts. Returns every post tag of your publication with its ID, name and slug; readers see tagged posts on /t/{slug}. hidden tags group posts without a public page. Pass tag_id to tag_post.

Takes no parameters.

list_posts

List posts

Posts of your publication, newest first, with status and audience. Lists posts of your publication, newest first. Filter by status to see drafts or scheduled posts. Scheduled posts include their publish time. Pages hold up to 50 posts; pass next_cursor back as cursor for the next page.

Parameterslimitcursorstatus

list_recommendations

List recommendations

Publications you recommend, or that recommend you, with the subscribers each sent. Returns Audience > Recommendations: with direction given, the publications you recommend; with received, the ones recommending you, and whether you recommend them back (mutual). subscribers_sent counts subscribers the recommendation brought. The table is rebuilt by Substack in the background, so a recommendation made minutes ago may be missing while counts already include it; publication_id checks one recommendation of yours directly.

Parametersdirectionpublication_id

list_sections

List sections

Sections of your publication, the separate newsletters inside it. Returns each section with its ID, name, description and slug. live is false while Substack still sets a new section up. subscribed_by_default tells whether new subscribers get its emails. A publication without sections returns an empty list.

Takes no parameters.

list_subscriber_tags

List subscriber tags

Tags you use to group subscribers. Returns the subscriber tags of your publication with their IDs, as Audience > Subscribers > Tags shows them. Subscribers never see tags. Pass tag_id to tag_subscribers.

Takes no parameters.

list_subscribers

List subscribers

Subscribers with plan, start date and activity rating. Lists subscribers, newest first, from the subscriber dashboard. Activity rating is the 0 to 5 score Substack shows there. Pages hold up to 500 rows; pass next_cursor back as cursor. The plan and since filters apply inside each page, so a filtered page can be short or empty while next_cursor still points further. Someone added a minute ago may not show yet: Substack fills the table in the background. paid includes founding members.

Parametersplanlimitsincecursor

list_subscriptions

List subscriptions

Publications you subscribe to, with your plan and whether their emails reach you. Returns every publication your account subscribes to, as Settings > Subscriptions lists them: name, link, plan (free, paid, comp, founding or gift, as Substack names the membership) and whether you get its emails. Your own publications are left out.

Takes no parameters.

list_traffic_sources

List traffic sources

Where your publication's visitors came from in a period, most views first. Returns Analytics > Traffic > Traffic sources: each source (the app, email, a website, search, social) with its category, views, unique visitors and the free and paid subscribers it brought. Sorted by views; page with next_cursor.

Parameterslimitcursorperiod

pin_comment

Pin comment

Pin a comment to the top of your post's comments, or unpin it. Pins one comment on a post of your publication above all others, as Pin in the comment menu does, or unpins it. A comment on someone else's post returns an error.

Parametersunpincomment_idrequired

publish_note

Publish Note

Short post in Substack Notes, now or at a set time, optionally with a link card to one of your posts. Posts a Note under your name. Without publish_at it goes out now; with it, the Note waits in your scheduled Notes, status is scheduled and published_at is that time. Text is 1 to 1,000 characters. link_post_id must be a published post.

Parametersbodyrequiredpublish_atlink_post_id

publish_post

Publish post

Publish a draft now. Publishes a draft immediately, on the web and, unless send_email is false, by email, to the audience set on the draft. Substack's own pre-publish check runs first; a missing title or an empty body stops the call. A sent email cannot be recalled. On a publication with sections the post goes to section_id, else to the section already set on the draft, else to the main publication.

Parameterspost_idrequiredsection_idsend_email

recommend_publication

Recommend publication

Recommend another publication to your readers, or stop recommending it. Adds a publication to your Recommendations, as Growth > Recommendations does: Substack suggests it to people who subscribe to you and notifies its author. blurb is the short reason readers see. With remove it takes the recommendation back.

Parametersblurbremovepublication_idrequired

remove_comment

Remove comment

Remove someone's comment from your post as the publication's moderator. Hides a comment on a post of your publication, as Remove in the comment menu does: readers see that a moderator removed it, the text is gone, replies under it stay. Use delete_comment for your own comments. A comment on someone else's post returns an error.

Parameterscomment_idrequired

remove_subscriber

Remove subscriber

Remove one email from your subscriber list. Removes a subscriber from your list, as Remove in the subscriber's menu does: they get no more emails from you and no notice. A paid subscription is cancelled and Substack refunds the unused part. An email not on your list returns an error; add_subscriber takes about a minute before the address is listed.

Parametersemailrequired

reply_to_comment

Reply to comment

Reply as you under a comment on your post. Posts a reply under one comment on a post of your publication, under your name, visible to everyone who can read the post. A comment elsewhere on Substack returns an error. The author gets Substack's usual reply notification.

Parametersbodyrequiredcomment_idrequired

reply_to_note

Reply to Note

Reply as you under any Note or Note reply. Posts a reply under a Note (yours or anyone's) or under a reply to one, visible to everyone who sees the Note. Text is 1 to 1,000 characters; Markdown bold, italics and links work. The author gets Substack's usual notification.

Parametersbodyrequirednote_idrequired

schedule_post

Schedule post

Publish a draft at a set time, on the web and by email. Schedules a draft to go live at the time you set, on the web and, unless send_email is false, by email, to the audience set on the draft. The time needs a time zone and must be in the future. Substack's own pre-publish check runs first; a missing title or an empty body stops the call. A scheduled post stays editable until it goes out. On a publication with sections the post goes to section_id, else to the section already set on the draft, else to the main publication.

Parameterspost_idrequiredpublish_atrequiredsection_idsend_email

search_substack

Search Substack

Search all of Substack for people, posts and Notes. Runs Substack's search as the search box does and splits the results into people, posts and Notes. Use the IDs with follow_user, like_post, like_comment, reply_to_note, send_message or recommend_publication. Page with next_cursor; later pages may hold only posts and Notes.

Parametersqueryrequiredcursor

send_message

Send message

Send a direct message on Substack, in a conversation or to a person. Sends a private chat message under your name. With conversation_id it replies there; with user it writes to that person, in your existing conversation with them or a new one. Someone who does not follow you gets it as a message request. Give one of conversation_id or user. A sent message cannot be recalled.

Parametersbodyrequireduserconversation_id

tag_post

Tag post

Add a tag to a post, or take it off. Puts one of your post tags on a draft or published post, or removes it with remove. A post can have several tags. Tagging twice keeps one tag.

Parametersremovetag_idrequiredpost_idrequired

tag_subscribers

Tag subscribers

Put a tag on subscribers by email, or take it off. Adds one of your subscriber tags to up to 50 subscribers, or removes it with remove. Emails not on your list come back in not_found and nothing else fails. A subscriber added a minute ago may not be findable yet; try again shortly.

Parametersemailsrequiredremovetag_idrequired

unpublish_post

Unpublish post

Take a published post off the web and back to drafts. Turns a published post back into a draft, as Unpublish in the editor does: it leaves your site, archive and the Substack app, and its link stops working. Comments and stats stay with the draft. Emails already sent stay in inboxes. Publish it again with publish_post. A post that is not published returns an error.

Parameterspost_idrequired

update_draft

Update draft

Change the title, subtitle, body or audience of a draft. Changes the fields you pass and leaves the others as they are. body_markdown replaces the whole body. Drafts and scheduled posts only: a published post returns an error. Nothing reaches your subscribers, so it runs without asking.

Parametersfieldsrequiredpost_idrequired

Version history

2
  1. v1.0.2LatestOct 24, 2026
  2. v1.0.0Oct 23, 2026

Score

90% of the applicable checks met

How complete this listing is, computed from the registry entry, the endpoint and public sources. Not a rating of the server and not a statement that it is safe or working today: reachability is a dated check, and no installs or reviews go into the score.

  • Reached in the last 30 daysRequired25 pts
  • Auth declaredRequired10 pts
  • Tools listed15 pts
  • DescriptionRequired15 pts
  • Logo10 pts
  • Documentation15 pts
  • License10 pts

    Declare a license in the repository or the registry entry.

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