How to Move Wagtail Blog to Substack

Moving from Wagtail to Substack means turning a blog archive into an owned email newsletter — with a public Substack home page and posts that arrive in readers’ inboxes.

Why leave Wagtail for Substack?

Wagtail is a strong CMS; Substack is lighter for independent newsletters.

Substack gives you hosting for posts, email delivery, paid subscriptions, and a simpler writing workflow. The missing piece for many authors is automation: Substack has no official public posting API. That is where API Substack fits.

How API Substack helps the move

API Substack is the unofficial posting API for Substack authors. After you create a Substack publication, you connect it to API Substack and republish your archive as drafts/posts — then keep shipping new issues without living in the browser editor.

• Register on API Substack and generate an API key
• Connect your Substack publication (publication URL + `substack.sid` session cookie)
• Create drafts, publish now, or schedule posts from API, CLI, or MCP
• Turn the migration queue into a repeatable newsletter workflow

In practice: export from Wagtail → create Substack → connect the publication to API Substack → republish cleaned posts → keep writing as a Substack newsletter.

Step 1 — Export from Wagtail

1. Export Wagtail pages/blog entries via management commands or admin export.
2. Copy media from Wagtail’s media storage.
3. Export subscribers from your ESP.
4. Convert StreamField blocks to linear HTML/Markdown.

Step 2 — Create your Substack publication

1. Create a publication at Substack and choose your name/URL
2. Write About / Welcome posts so new subscribers understand the move
3. Import your subscriber CSV in Substack (where you legally have consent)
4. Optionally connect a custom domain in Substack settings

Step 3 — Connect the publication to API Substack

1. Register on API Substack and start your key
2. Set your publication URL (example: `https://yourname.substack.com`)
3. Copy the browser cookie `substack.sid` while signed into Substack (DevTools → Application → Cookies)
4. Store the API key + cookie in your CLI, HTTP client, or Substack API MCP

Step 4 — Republish Wagtail posts to Substack

1. Clean each post (title, subtitle, body, images, tags)
2. Create a draft on Substack via API Substack (`create_post` / draft flows)
3. Review the draft in Substack if the piece is sensitive or heavily formatted
4. Publish or schedule — work oldest→newest or ship a “best of” first
5. Announce the move to remaining Wagtail readers with the Substack URL

For non-technical authors, install the MCP into Claude, Cursor, or Codex and ask the agent to draft/publish. For developers, use the Python client / CLI or raw HTTP. See How to post to Substack via API.

Corner cases

• StreamField complexity is the main cleanup cost.
• Keep Wagtail for the org site if only the blog moves.
• Paid Wagtail gatekeeping → Substack paid posts.

• `substack.sid` expires — refresh it when you get 401/403
• API Substack does not replace Substack’s own subscriber CSV import — connect the publication, then republish content
• Image upload and Notes are not the focus of the posting API — optimize for newsletter posts
• This is unofficial and not affiliated with Substack — keep browser login as backup

After the move

Once the Wagtail archive is on Substack, keep using API Substack as your publish rail: draft tomorrow’s issue, schedule the week, or let an AI agent post through MCP. Your blog becomes a Substack newsletter you actually control.