Platypub: email newsletters for personal blogs

A few weeks ago, I finished a version 2.0 release for my web framework, Biff. Due to the whole job + kids thing, I'd been pretty much working on that for the past two years. Now that it's done, I've finally been getting back into actually working on my own web apps again.

And the first thing on my list has been to do another rewrite of Platypub, my "blog newsletter thing." The prior releases:

• Announcing Platypub (2022)
• Platypub: back to square one (2024)

In a nutshell I want a publishing tool kind of like Wordpress / Ghost / Substack that lets me write blog posts and send email newsletters. I want complete control over the theming. I want the marginal cost of a blog/newsletter ("publication") to be cheap/basically free. I want the ability to host a single instance that serves many users, like a Mastodon server.

The first version of Platypub was this monstrous thing that let you not only define themes as custom code but even let you define the data model, similar to a CMS. That ended up being a bit unwieldy, so after a while I scrapped it and tried to (re)start out with something much smaller: a CLI tool with commands for generating and publishing a static website from a set of markdown files. In both cases, the newsletter bit was handled via Mailgun's mailing list feature, which let me offload subscriber management and unsubscribe handling completely to Mailgun.

I recently discovered that Mailgun had introduced a limitation for whatever plan I am/was on so that you can only have 100 subscribers on each mailing list, so it turns out that new subscribers were being dropped silently. So I set up and migrated to a Listmonk instance. Which is ok but not where I want to be forever.

After I released Biff 2, I started using it to make a new version of Platypub that handles just the newsletter part and not the blog part. You give it a link to your blog, then Platypub sets up a newsletter based on the blog's RSS feed. Platypub gives you a hosted, captcha-protected signup form (example) which you can either link to or embed on your website. When new posts are published on your blog, they get sent to subscribers automatically.

Publishing a blog without a newsletter is relatively simple; it's the email newsletter thing that has more moving parts. So this makes it really easy to plop a newsletter on to whatever blog you already have, wherever it's hosted (could be a static site, could be wordpress, ...). I like the idea that this could make newsletters more prevalent in personal blogs, since email is the only widely adopted method for subscribing to content that isn't owned by a single platform.

To deal with spammers, my plan is that you wouldn't be able to import an existing subscriber list unless you pay a one-time fee. Most people don't already have a newsletter, so all their subscribers will have come from Platypub's hosted signup form which can do its own anti-spammer stuff. I'm hoping that strikes a good balance. Other than that, pricing would probably be based solely on number of emails sent per month, with some free allowance like 500 emails per month or something. I'd want Platypub to be able to fund its own existence; it wouldn't be intended to make more many than necessary for that. Ideally, other people would host Platypub instances that are available for public use, similar to Mastodon.

For now, you can technically sign up for Platypub, but it's in "wait list" mode. If I ever take it out of wait list mode then you'd get an email notification. The code is technically over here so those inclined can self-host, however I probably wouldn't recommend it just yet since it's still very much alpha-quality software. I just barely got it functional enough that I could migrate my own websites to it. The spec might be interesting if you're really into this kind of thing.

Eventually I'd like Platypub to also have blog functionality so you can write posts in it and such, but carving out the newsletter part seems like a good place to start. Again.