Xfers is the easiest way to accept payments online in South East Asia. See https://xfers.com for details.

Easy validation and processing of Paypal IPN payments

alpha - currently covers part of payments pro and all of mass pay

A simple gem for creating customers and charges using pin-payments (pin.net.au) API

Stairs plugin for setting up Balanced Payments

Rails integration for Ripple payment notifications.

Jamm help you make payment without credit cards

Command line client for Ripple payment platform

Ruby library for integrating with the Stone payment web services.

Midtrans payment gateway for Spree framework

A Ruby gem for simulating Point of Sale operations in Clover sandbox environments. Generates realistic restaurant orders, payments, and transaction data for testing integrations with Clover's API.

Dolla is a gem that provide payments methods for bank gateways.

Ruby gem for Rent$ payment Gateway & Intermediary

A lightweight Ruby library for interfacing with the eWAY Token Payments API.

When your customer doesn't want e-commerce but actually you need products, orders and a payment gateway

An API for using the Amazon Flexible Payment Service (FPS) - updated for version 2008-09-17 of the API.

Integration of Braintree payment gateway for use with Piggybak

GoCoin is the best way to accept Bitcoin payments for online businesses. See https://gocoin.com for details.

A wrapper for PintPay's payment API and webhooks.

Paytrail Merchant API allows merchant to create and delete refunds for payments made via Paytrail