Sandbox Pay от David Nguyen

Features
PayPal Sandbox cards — Generate random valid test cards (Visa, Mastercard, Amex, Diners, Maestro, CUP, JCB) with Luhn-valid numbers
PayPal error triggers — One-click fill for PayPal-specific error codes (CCREJECT-REFUSED, CCREJECT-SF, etc.)
Stripe test cards — Full list of Stripe test cards categorized by Success, Decline, and 3DS
Auto-fill — Automatically fills card number, expiry, CVV, cardholder name, and country into payment forms
Context menu — Right-click on any input field to fill card data directly
Customizable settings — Set default country, cardholder name, and card background images
i18n — Supports English and Vietnamese