Sync any blog via API to Substack in one-click
I create an api libruary what can help you sync any blog to Substack
in one-click. Notes, Articles included. 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.
Full doc: https://apisubstack.com/
It can:
• Create note
• Delete note
• Create draft / publish / schedule
• Create draft (low-level)
• Delete draft
• Pangram AI / AI-slop check
• Verify auth / profile
• Get draft
• Update draft
• Publish now
• Schedule
• List tags
• Create tag
• Attach tags
• Get post tags
Every Substack client method
Rate limit for every endpoint: 1 request per second.
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.
This solves a real pain point for anyone publishing regularly on Substack. The ability to draft, schedule, publish, and manage tags programmatically without living in the browser editor is genuinely useful.
One question I'd have is around authentication stability. Since it relies on the substack.sid session cookie, how often do users need to re-authenticate, and how resilient is it to changes on Substack's side?
Also, have you found that most users prefer the Python client, CLI, or MCP server? I'd be curious which workflow gets the most adoption.
The session cookie auth approach is the pragmatic choice here — Substack doesn't have a proper OAuth API so you're working with what exists. One thing that bites automation tools built this way: the substack.sid cookie expires, and when it does, the failure mode is silent (returns 200 with a redirect instead of an error). Have you built in any auth validation step that catches that before a scheduled post just silently fails?