You can pay with a credit or debit card. Safebooru uses Stripe as a payment intermediary so none of your personal information will be stored on the site.

<% if user.level < User::Levels::GOLD %> <%= stripe_button("Upgrade to Gold", 2000, user) %> <%= stripe_button("Upgrade to Platinum", 4000, user) %> <% elsif user.level < User::Levels::PLATINUM %> <%= stripe_button("Upgrade Gold to Platinum", 2000, user) %> <% end %>