But I am just curious as to whether you are just sharing this because you yourself came across it, or if you are the owner of it, or something has changed, as the site is not new. I've come across miniature.io a few times in my research for different products that I was interested in making, particularly having to do with screenshots.
Your website inspired me to actually add PDF screenshots of webpages to my site, pixle.com, although I am finding that some dynamic websites that have animated CSS and things like that are not very good at "letting the page load first" and then capturing the screenshot, so I end up with a blank PDF or a PDF with some assets loaded on it, but not a complete website.
To be absolutely honest, I posted a link to the website here as I have never done it previously. Built it years ago, because at the time I found this topic challenging to implement and worth trying. For years the system was online and free to use, serving even 2 million images daily. Free of charge. I didn't know whether I should kill it or spend some more time finally finishing the commercial part. Done the latter over the last couple of months and so here it is, polished a bit with a new rewritten website renderer.
If you were looking for a simmilar projects, or simply interested in the tech behind it, you can have a look at https://github.com/cepa/rabarbar this is the current engine that captures screenshots.
That is quite a few users you've got. And I've learned for monetization: it's nice that people get to jump on your back and you carry them for the ride, but after a while, its gets old and you lose motivation to keep working. Sounds like socialism. In theory it works great, but if you're the only one paying for it... while everyone but you gets to benefit. Eventually, you get to a point where you ask, "What's the point?" Some might love a sacrifice for the greater good... but hey, you got to eat and pay your rent and enjoy life a few weeks out of the year too! I think it's okay to tell people that you need to get paid for your work. Good luck!