It is worth pointing out that Libgen doesn’t have everything, just a portion of books that have been digitized by publishers. For older and now out-of-print books, or for genres like poetry where only a few authors are ever given the ebook treatment, you won’t find that content on Libgen unless someone does the work of scanning it. And even if someone does scan it, you’re going to just get a PDF or DJVU file, not a beautifully formatted EPUB for your e-reader.

I have been a Libgen user and contributor for many years now, but I find myself simply buying more and more physical books, since so much of what I want to read is not available on Libgen or anywhere else digitally.

I’ll leave finding DRM-free ebooks as an exercise for the reader. There are a number of small publishers offering their books without DRM. Some genres are easier than others.

Tor went DRM-free many years ago. I know their catalog is on Amazon.

Sorry, I just realized that question was poorly stated. It misses an important point: there has to be a decently sized catalog. It doesn't need to rival Libgen, but it should be something that covers most of your bases. Sorry for kinda moving the goalposts here, but right now, most of the time, looking for a particular book you can't get your hands on it DRM free without going to Libgen. That's the thing which has to change.

If you're looking for tech-related ebooks, check out ebooks.com. There's 49185 in their technology category that's DRM-free, including O'Reilly books.

I did not find the book they wanted on libgen. Libgen is not perfect.