Show HN: The Posting Substack API
This article introduces a new API for Substack authors to programmatically draft, publish, and schedule posts. It offers three products: Python client, CLI, and MCP server, with integrations for AI tools like Cursor and Claude. Pricing is $9/month after a 7-day free trial with unlimited API calls.
API Substack — Posting API for Substack authors
Onboard your Agent to SubstackWorks with Claude, Codex, Cursor, and OpenCode
The Posting API for authors to draft & publish!
and ship without opening the editor.
ask_
Sign in, start a free trial, then get your API key.
Substack authors posting via API...
12K+
Posts created
Posts created
4.5K+
Newsletters sent
Newsletters sent
28K+
Drafts written
Drafts written
10
Integrations
Integrations supported
Posting
Substack posting automation – solved
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For Substack authors who need to post from code — draft, publish now, or schedule. That is the job to be done. Tags and draft updates support the same posting workflow.
POST /api/v1/drafts PUT /api/v1/drafts/{id} GET /api/v1/drafts/{id}/prepublish?publish_date=... (schedule) POST /api/v1/drafts/{id}/scheduled_release (schedule) POST /api/v1/drafts/{id}/publish (publish now)
For authors
Built for Substack authors
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If you write and publish a newsletter, this is for you. Connect your publication, authenticate with your session, and post without living in the browser editor.
• Verify auth / profile • Create draft / publish / schedule • Get draft • Update draft • Publish now • Schedule • Delete draft • List tags • Create tag • Attach tags • Get post tags
Products
Python client, CLI, and MCP
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Three separate products for the same posting job. The Python client for scripts and apps. The CLI for the terminal. The MCP server for AI tools such as Cursor or Claude. Pick one product — they are not the same package.
• Python client: Standalone Python SDK for Substack authors who post from scripts and apps. • CLI: Standalone command-line tool for draft, publish, and schedule from the terminal. • MCP server: Standalone MCP product for posting from AI tools such as Cursor or Claude. • Plain-text → ProseMirror draft_body conversion • Universal publication_url (*.substack.com or custom domain)
Pricing
One simple plan for Substack authors. Try free for 7 days, then $9 per month. Unlimited API calls across MCP, CLI, Claude Code, Claude Cowork, Cursor, and ChatGPT-compatible clients.
API Substack
7 days free
• Unlimited API calls
• Posting
• Drafting
• Deletion
• Creating tags
• MCP compatible
• CLI compatible
• Claude Code / Cowork
• Cursor compatible
• ChatGPT compatible
7 days free — then $9 per month
Start free — $9/mo after
Very frequently asked questions
Who is this for?
Writers and newsletter operators who publish on Substack and want to post with the Python client, the CLI, or the MCP server — each a separate product. If your job is to get posts out of your head and into your publication — this product is for you.
What job does this close?
Help Substack authors post to their publication programmatically — draft, publish, and schedule without the browser UI. Supporting actions (update draft, delete draft, tags) exist to make that posting workflow complete.
How do I post with it?
Authenticate with your browser session cookie (substack.sid), set your publication URL, then create, publish, or schedule with one of the separate products: Python client, CLI, MCP server. Each is its own product — pick the one that fits your workflow.
Join authors who post via API
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Sign in, start a free trial, then get your API key.
Partners
API Substack
The posting API for Substack authors — draft, publish, and schedule posts from code.
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