GearUp uses Stripe to process all credit cards. All card numbers are encrypted at rest with AES-256. Decryption keys are stored on separate machines. None of Stripe’s internal servers and daemons are able to obtain plaintext card numbers; instead, they can just request that cards be sent to a service provider on a static whitelist. Stripe’s infrastructure for storing, decrypting, and transmitting card numbers runs in separate hosting infrastructure and doesn’t share any credentials with Stripe’s primary services (API, website, etc.).
You can learn more about this here.