Substack and Platform Risk

Michael Hartl • Jul 5, 2023

Some years ago, I started a blog for the Ruby on Rails Tutorial using a blogging platform created by a friend of mine. Unfortunately, the platform was acquired and then shut down, stranding all of my posts. Exporting and reuploading them was a giant pain in the neck. The experience was so unpleasant that I resolved never to let it happen again.

As noted in the recent 2023 State of the Tau newsletter, I started my own Substack both to make tau-related announcements and to discuss math and math learning. Substack has some of the same issues as the defunct platform mentioned in the previous paragraph, though. Moreover, even if (as seems likely) Substack continues to thrive as a business, the thought of having my posts trapped in its proprietary editor makes me deeply uncomfortable.

As a result, my current plan is to publish most posts on my website,, which uses the Jekyll static site generator with plain-text posts stored in a Git repository. In order to minimize friction, I expect to use Substack for short summaries and email notifications for the posts but not for the full posts themselves; rather than trying to keep full copies in both places, the canonical version of the full post will be at

This issue didn’t come up with the State of the Tau newsletter since historically I’ve published that both as an email and at, but constantly having to keep two posts in sync is simply more trouble than it’s worth. Moreover, publishing the main posts exclusively at has the additional advantage of allowing me to use full-strength mathematical typesetting with LATEX, using both MathJax and my own jekyll-latex plugin.

For example, the online version of this post (i.e., this one) has a slick inline copy of the time-independent Schrödinger equation here: \( \left(-\frac{\hbar^2}{2m}\nabla^2 + V\right)\psi = E\psi \). Unfortunately, Substack simply isn’t cool enough to manage it. (It’s not really Substack’s fault: by design, Substack posts have to render properly inside email clients, so the only LATEX support they currently offer is centered math, which is rendered with MathJax in browsers and with embedded images in emails.)

One result of this is that, barring a change in policy, posts will generally be available for free at Paid subscribers to my Substack will still get concrete benefits, though, including:

  • Email notifications for any subscriber-only posts

  • The satisfaction of supporting my work financially

  • The ability to comment on select posts

  • The ability to send me messages by replying to any Substack email

That last bullet point deserves a brief comment. My email address isn’t that hard to track down (or guess), but there’s always a question about whether an unsolicited email would be welcome. In contrast, paid subscribers can reach me through Substack by responding via email to any of these announcements. Perhaps more importantly, paid subscribers are invited to do so, which means you know you won’t be bothering me if you do (at least, not unless you really try—please don’t take this as a challenge!).

So, if you’d like to get the above benefits, please consider upgrading to a paid subscription if you haven’t already. In any case, stay tuned for lots of upcoming posts on math and math learning!

1. If you’re a paid subscriber, please let me know if you have any objections to this. I could easily arrange for subscriber-only posts at using secure URLs.