From Substack to Squarespace: A Developer's Guide to a Seamless Migration

There is no button that says “Move my Substack to Squarespace.”

If you’ve ever tried, you already know that. You get a CSV. You get a pile of HTML files. And Squarespace politely tells you it only wants WordPress XML. That mismatch is where most migrations die.

I just finished moving 734 posts from Substack into Squarespace. This is how I did it, working alongside Manus AI, without losing dates, titles, or content, and without re-publishing everything by hand.