Does my card number end up on your servers?

No. Pressing a plan on Settings → Plan & billing hands you to Stripe's own secure page — the card is typed there, not here, and what comes back to us is the brand and the last four digits, which is exactly what your billing page shows you afterwards. Apple Pay and Google Pay work on that page too, so on a phone you often never type a number at all. It is also the ONE place a card is ever collected: signup never asks for one, and nobody from us will ever ask you for card details over WhatsApp or email.