Google Payment API - Enable an easy-to-use checkout experience for customers

Gemnote - Handwritten cards & premium custom gifts for companies

Giftbit Payment API - Stripe for gift cards

iwantdis - Tastefully curated products and gifts from the internet

Stripe - Online payment processing for internet businesses. Stripe is a suite of payment APIs that powers commerce for online businesses of all sizes. Use Stripe’s payment platform to accept and process payments online for easy-to-use commerce solutions.

Handwrytten - Handwritten notes straight from your device. Huge selection of cards or design your own. Handwriting service integrates with 1000's of apps.