Greg Zaal runs a website called HDRI Haven.
https://hdrihaven.com/
I first become aware of his work around October 2016, this probably coincided with him releasing a pack of a dozen or so HDRIs for free. I have used these HDRIs in production a few times since, and they offer outstanding quality.
They are all provided at 16k resolution, and range from 6 to 24 EV exposure range, provided as 32 bit .hdr files. It makes for effortless shading, and it was quite a generous gift to the community.
As as though that wasn't philanthropic enough, Zaal has gone ahead and made the entire library of his content available for free, with no hidden strings or claims to intellectual property. Not even attribution or mention.
In a humble attempt to support him, I will be committing funds to his Patreon account, but I'll also give him a bump here, in the hope that will further his cause.
It's terrific to see this kind of spirit in industry. Capitalism does not need to be a zero-sum game, but that does mean we have to get comfortable with the act of not always doing what brings maximum and immediate benefit to ourselves at all times, which is a very hard spell to break.
I encourage anyone interested or benefiting from this to read Zaal's blog post regarding his altruistic shift:
https://blog.hdrihaven.com/2017/10/01/why-the-change/
If you ever read this Greg, thank you for your skill, generosity, and hard work.