Stripe records user movements on its customers' websites

Stripe cofounder here. The question raised ("Is Stripe collecting this data for advertising?") can be readily answered in the negative. This data has never been, would never be, and will never be sold/rented/etc. to advertisers.

Stripe.js collects this data only for fraud prevention -- it helps us detect bots who try to defraud businesses that use Stripe. (CAPTCHAs use similar techniques but result in more UI friction.) Stripe.js is part of the ML stack that helps us stop literally millions of fraudulent payments per day and techniques like this help us block fraud more effectively than almost anything else on the market. Businesses that use Stripe would lose a lot more money if it didn't exist. We see this directly: some businesses don't use Stripe.js and they are often suddenly and unpleasantly surprised when attacked by sophisticated fraud rings.

If you don't want to use Stripe.js, you definitely don't have to (or you can include it only on a minimal checkout page) -- it just depends how much PCI burden and fraud risk you'd like to take on.

We will immediately clarify the ToS language that makes this ambiguous. We'll also put up a clearer page about Stripe.js's fraud prevention.

(Updated to add: further down in this thread, fillskills writes[1]: "As someone who saw this first hand, Stripe’s fraud detection really works. Fraudulent transactions went down from ~2% to under 0.5% on hundreds of thousands of transactions per month. And it very likely saved our business at a very critical phase." This is what we're aiming for (and up against) with Stripe Radar and Stripe.js, and why we work on these technologies.)

[1] https://news.ycombinator.com/item?id=22938141

> (CAPTCHAs use similar techniques but result in more UI friction.)

Not only are they inconvenient, but they're often inaccessible for some users. So I just wanted to say thanks for not going that way, even if the cost we must pay is some theoretical compromise in privacy.

Edit: On thinking about this some more, it occurred to me that by using a user's activities on a web page to determine whether they're a bot committing fraud, you might be inadvertently penalizing users that use assistive technologies, such as a screen reader, voice input, eye-tracking, etc. I haven't had a problem with this when doing a Stripe checkout with a screen reader, but I just wonder if this possible pitfall is something that your team has kept in mind.