I trust the Hubski crew. I sort of trust Stripe. I see the https protocol and the reassuring little padlock icon on the donate page.
But every time I start typing digits into that janky HTML form I get twitchy and close the tab. It's the same credit card I handed to a random camarero in Mexico City. I don't know what's wrong with me. I just can't do it.
I have some PayPal credit. I don't especially like PayPal and there are reasons to mistrust them. But I like to prowl eBay and it's just easier with PayPal. I've donated bitcoin, but bitcoin is a pain to acquire and I'd prefer to hold what I have left.
Convincing them Hubski is nonprofit involves some red tape, but that might be avoidable in the near term: "We make it easy to set up your site to take payments but to withdraw more than $500 a month you will need to verify your account."
They even support recurring donations.