Gumroad - where I self-publish my book (https://gum.co/deploymentfromscratch) - does the watermark automatically for PDFs.

That said, probably don't worry about it. I also release additional things (like code), and it's just there for anybody that bought it. I am fine with that.

It would take you a significant effort to prevent bad actors and you would likely make it worse for the your customers in the end. It's just something to accept.

I wouldn't worry about DRM. Think of shared copies as free advertising.

(a) who said anything about DRM and (2) free advertising schmee advertising. There's plenty of evidence to show that pirated books/movies/music/software don't lead to more sales.¹ My goal is to maximize freedom of the users of the book (if you buy a PDF copy, you should be able to have it on every device you own if you like), with a mild disincentive against sharing the files against the terms of the sale.

1. And please don't give me any of that Corey Doctorow–inspired stuff.² I've heard it all before. I've heard the other side too—I've seen friends' sales crater when a pirated copy of their book showed up on some site and then rebound after it was taken down.

2. As an aside, the one Doctorow book I've read was Pirate Cinema which was not good. I did read a long story of his in 21st Century Science Fiction which started out good and had an interesting premise, but ultimately failed to deliver on its promise. I've been told some of his other books are good though.

You can use Gumroad. You can add watermark (IIRC it based on customer's email) and customer will get book updates for free. You can also send email to the customers when you have a new version.

> there will likely be updates to LaTeX that will require some minor changes in the text as time goes by.

That’s probably not a big risk tbh.

There have been some significant changes just in the last year, most notably, the movement of the xparse package into the kernel and a preference for \NewDocumentCommand et al. over \newcommand and its relatives. Most of the changes happen below the user interface level, but occasionally the bubble up beyond that (right now, there's some discussion about the fact that \NewDocumentEnvironment{foo} will silently overwrite an existing \endfoo command and how best to manage this (I'm in camp issue an error. The other possibility is to modify the default mapping of \begin{foo}…\end{foo} which currently calls commands \foo and \endfoo to do something slightly different but this would break lots of legacy code and likely won't happen). The biggest area where changes would impact the book is the appendix of error messages. In at least a few cases I've had error messages change in this year's updates (partly because of my own reports to the core dev team).

> ideally, I'd like to have individually watermarked PDFs for each backer to act as a social deterrent to uploading the file to download sites

What if someone provides fake information then uploads the book with your watermark?

I'm not looking for perfect protection, just to keep honest people honest.

So, what happens when someone's watermarked copy starts showing up online? Will you be assuming the only way it got out was abuse by the intended customer and send in the lawyers? Did you notify your customers before they paid anything of this risk they're taking?

Most likely I'd send a polite e-mail letting them know that I saw this and reminding them that they aren't supposed to share the file. The expense of a lawyer wouldn't be worthwhile. You seem to assume nefarious intent. My goal is simply to be able to let people buy a DRM-free copy of the PDF with a mild disincentive against sharing.

Not necessarily "nefarious", but I certainly don't trust everyone to behave reasonably or logically. The very act of putting the watermark in will plant that idea in at least some of your customer's heads. And since you didn't answer my question about whether you informed customers of it before they made a purchase, I think it's safe to assume you didn't. Even if all of your customers trust you to act reasonably, you could die tomorrow and all of those rights will get transferred to someone else who may not be as trustworthy.

The watermark gets the backer's name on it, now the author's name on it.

I know that. You've misread my question. The idea is that the backer won't upload the PDF on file sharing websites because the author will find it and trace it back to the backer using the watermark. But if the backer was anonymous by means of fake information provided to the author at the time of purchase then it's not deterring anything.

Whoop, yeah, I did misread.

checkout bookfunnel: https://bookfunnel.com/ I'm not affiliated with them, just a happy customer.

This is what pragprog does, but I don't know any self-publishing platform that does the same. You can probably roll your own without much trouble, just using stripe for billing.