Fork is *not* free. At least it isn't free anymore.
On one of my Macs I got a friendly nag screen yesterday, asking(!) me to purchase Fork in order to fund further development of the application. I immediately checked on their website, and indeed - there is a price of 49.99$ listed, together with the subtitle 'free evaluation'. So at some point in time they obviously switched to a kind of shareware model - use is free within certain limits, but then they ask you to buy the software.
Which is exactly what I did, mostly because I like the tool and have used it for a couple of years now, and I think it's a fair price for the value.
While it's a pity that Fork isn't free anymore, I really appreciate that I now have a sensible option to support its development and contribute to Fork becoming better and staying in the market instead of becoming another tool I have to replace sooner or later. I hope some more users will follow suit.