I just played at
https://www.joker21.com - BlackJack for CLAM.
People in the Just-Dice chat were complaining it was "rigged" and asked me to go check it out, so I did.
I didn't identify myself there, just turned up as a random player. There's a faucet which sometimes gave me 5000 clamtoshis and sometimes just 1337, but either way that's enough to try the site out.
The dealer got lucky a few times, but that happens. I was able to turn my 5k to 20k before busting it.
Then I deposited 10 CLAM, and was able to bet 1 CLAM a few times, getting up to 11 or 12 CLAM before the max bet dropped below 1 CLAM. I bet 0.8 CLAM a few times and ended up withdrawing 10.6 CLAM. The withdrawal was instant.
The site appeared to crash a couple of times while I was playing, the animations are a bit glitchy, when the dealer has an ace it shows as being worth "1/10" when it should be "1/11", and CBI was complaining of losing a hand where he split 10's, got a 21, and lost to a 5-card 21 by the dealer. "Dealer 5 card Charlies aren't a thing" or something.
More seriously, I couldn't see the rules listed anywhere on the site, and there's nothing about how the probable fairness works. It shows you a sha256 hash of a list of cards before you play, and publishes the list of cards afterwards, but there's also a client seed (integer) and no indication of how the client seed affects the shuffle. So it's maybe provably fair, but there's not enough information on the site to know for sure, since I've no idea how to verify the deals.