A number of fully-tested clients for interacting with all of the available postcode anywhere services, including capture, cleansing, payment validation and email validation

Performing multiple payments to PayPal using the MassPay API

Payment Gateway to Paybox's services

PayPal Client.

Simple SDK interface to create transactions for the Pay.nl payment service provider.

[Deprecated] The PayPal Button Manager SDK provides Ruby APIs to create, and manage PayPal Payments Standard buttons programmatically.

Payfort Start is the easiest way to accept payments online in the middle east. See https://start.payfort.com for details.

A gem for e-payment systems API's and SCI's

A think wrapper of PayDesign API for convenience store payment, pay-easy and some more.

A Ruby library for interacting with v1 of the Pin Payments API

Provides an implementation of the Pin Payments API (pin.com.au) for Ruby and Rails projects

Postino allows you to generate Italian postal payment forms in PDF format using Prawn.

Provides complete access to PayPal's Adaptive Payments API

Integration with Przelewy24 payment gateway.

Add social payments to your business by adding a ‘Pay with Pygg’ button to your site!

Use Stellar payment channels in Ruby with ease

The PayPal REST SDK provides Ruby APIs to create, process and manage payment.

With moolah.io you can process payments in-store and online. Rmoolah is a API wrapper for moolah.io

rocketgate-ruby is a simple interface for communicating with RocketGate's Payment Gateway

Merchant signature calculator for Adyen (https://www.adyen.com) payments service. It is implementation of HPP HMAC (SHA-256) algorithm from Adyen documentation (https://docs.adyen.com/display/TD/HPP+HMAC+calculation).