How can I embed a Substack newsletter sign-up form onto my Webflow site using HTML? I've tried adding the code to the head tag following the instructions from the Webflow University article on custom code but it doesn't seem to be working. Any advice?
TL;DR
- Paste the Substack script into Webflow’s Custom Code Head section in Project Settings.
- Add the HTML form or iframe into an Embed element on your page in the Designer, then publish the site to view it live.
You're trying to embed a Substack newsletter sign-up form in your Webflow site, but it's not displaying correctly even after adding the code to the head tag. Substack embed forms usually involve both a script in the <head> and HTML markup in the <body>—both parts must be placed correctly for it to work.
1. Add the Substack Script to the Site Head
- Go to Webflow dashboard, open your desired project.
- Click Project Settings > Custom Code tab.
- Under Head Code, paste only the script portion from Substack (starts with
<script src=...). - Save changes and publish the site (changes won’t show in preview mode).
2. Add the Embed Form HTML in the Page Body
- In the Webflow Designer, select the page and section where you want the form to appear.
- Drag an Embed element from the Add panel to that section.
- Paste the Substack form HTML code here (typically includes a
<form>tag with some styling or an iframe). - Click Save & Close, then Publish your site.
3. Confirm You're Using the Full Embed Code
- Go to your Substack dashboard: Settings > Import/Embed > Embed signup form.
- Copy the entire code, then split the parts:
- Script (in head): Goes in Project Settings > Custom Code > Head Code.
- HTML markup (form): Goes in an Embed block in the Webflow Designer.
If Substack provides an iframe version, you can paste the <iframe> directly inside the Embed block without needing any script.
4. Publish to See Changes
- Embedded forms won’t appear in Webflow’s Designer preview.
- You must Publish your site and view it on the live domain (yourwebflowdomain.webflow.io or connected custom domain).
5. Troubleshooting Tips
- Double-check for missing or misplaced tags (e.g., don’t put full HTML documents into the Embed block).
- Ensure your browser or an extension isn't blocking external scripts.
- If the form still won’t work, try using Substack’s iframe embed version, which is simpler and less likely to break.
Summary
To embed a Substack sign-up form in Webflow, place the script in the Head section of Project Settings and the form markup or iframe inside an Embed element in your page body. Then publish the site to make it live.