Your posts and your subscriber list, with paid and free clearly marked: from the export under Settings.
The subscriber list is minutes. The archive depends on how much you have written, usually under an hour.
posts.csv (plus the posts/ folder beside it)
read locallyThis is a Substack posts export
We can tell from the columns and the file name.
Posts
128 of 129 ready128 posts ready: 1 row will be skipped.
Row 84: this record has no name.
Nothing has been saved yet.
Ten percent of subscription revenue, plus payment processing. At a hundred subscribers it is a rounding error. At three thousand it is a salary.
The design, the URL structure, the recommendations pointing readers at other people's newsletters. You are a tenant with good furniture.
It is a newsletter. Not a shop, not a course, not a members area, not a business, and every one of those is where a newsletter that works eventually goes.
Everything in this list is something an importer we maintain actually reads out of your Substack export. It is generated from that importer, so it cannot promise you something we do not do.
Posts
Settings → Exports → Create a new export
posts.csv (plus the posts/ folder beside it)
Subscribers
Subscribers → Export → All subscribers
email_list.csv
sparx sends the newsletter, hosts the site, takes the payments and runs the shop, for a flat monthly fee that does not care how well you are doing. The same list, on infrastructure you own.
Paid and free subscribers arrive tagged as such, so you can mail them differently from day one.
A flat fee instead of a percentage: at three thousand paid subscribers that is most of a salary back.
Sell a book, a course or a workshop to the same list, without a second platform.
Every migration leaves something behind. Here is ours, so it is not a surprise halfway through.
Substack's posts.csv is an index: the writing is in HTML files beside it. Drop the whole export folder so the bodies come too.
Paid posts arrive as drafts rather than public, so migration day does not put your paywalled archive on the open web.
Stripe billing is re-connected here; existing subscriptions do not transfer automatically.
Still curious? Read the platform docs, browse the API spec, or book a 20-min architecture call. We don't do high-pressure demos.
No. Everything happens on a copy. You export a file, and your Substack account carries on exactly as it is. Plenty of people run both for a few weeks before switching their domain over.
Export the file Substack already makes for you, drop it in, and look at what would happen before anything is saved. The subscriber list is minutes. The archive depends on how much you have written, usually under an hour.