Active Merchant is a simple payment abstraction library used in and sponsored by Shopify. It is written by Tobias Luetke, Cody Fauser, and contributors. The aim of the project is to feel natural to Ruby users and to abstract as many parts as possible away from the user to offer a consistent interface across all supported gateways.

Stripe is the easiest way to accept payments online. See https://stripe.com for details.

Stripe, Paddle, and Braintree payments for Ruby on Rails apps

Resources and tools for developers to integrate Braintree's global payments platform.

Additional Payment Gateways for Spree Commerce

Mountable rails engine which loads assets (svg files of payment icons) and provides a frozen_record model called PaymentIcon to access these through groups, names of icons, etc.

If you are tracking any kind of assets the currencies gem is for you. It contains every currency in the ISO 4217 standard and allows you to add your own as well. So if you decide to take sparkly buttons as a form of payment you can use currencies to display the shiny button unicode symbol ☼ (disclaimer: ☼ may not look like a shiny button to everyone.) when used with something like the money gem. Speaking of the money gem, currencies gives you an ExchangeBank that the money gem can use to convert from one currency to another. There are plans to have ExchangeRate provider plugin system. Right now the rates are either set manually or pulled from Yahoo Finance.

Offsite Payments is a simple abstraction library used in and sponsored by Shopify. It is written by Tobias Luetke, Cody Fauser, and contributors. The aim of the project is to put as simple an abstraction as possible on top of offsite (often called hosted) payment pages, and allow contributors to easily help services such as Shopify extend the number of offsite payment services they support.

PayPal Express Checkout API Client for Instance, Recurring and Digital Goods Payment.

Receipts for your Rails application that works with any payment provider.

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

Authorize.Net SDK includes standard payments, recurring billing, and customer profiles

Implemention of Payments Initiation (ISO 20022)

Lightweight wrapper for Paypal's Adaptive Payments API

Package to simplify including the Adyen payments services into a Ruby on Rails application. The package provides functionality to create payment forms, handling and storing notifications sent by Adyen and consuming the SOAP services provided by Adyen. Moreover, it contains helper methods, mocks and matchers to simpify writing tests/specs for your code.

A rails plugin to add an active_merchant patch for china online payment platform

Ruby client library for the GMO Payment Platform.

Package to simplify including the Adyen payments services into a Ruby on Rails application. The package provides functionality to create payment forms, handling and storing notifications sent by Adyen and consuming the SOAP services provided by Adyen. Moreover, it contains helper methods, mocks and matchers to simpify writing tests/specs for your code. Fork version with payouts implemented.

[Deprecated.] The PayPal Merchant SDK provides Ruby APIs for processing payments, recurring payments, subscriptions and transactions using PayPal's Merchant APIs, which include Express Checkout, Recurring Payments, Direct Payment and Transactional APIs.

In the last few years digital currencies have successfully demonstrated their ability to become an alternative financial instrument in many different markets. Most of the technologies available at the moment are based on the principles of Blockchain architecture, including dominating currencies like Bitcoin and Ethereum. Despite its popularity, Blockchain is not the best possible solution for all scenarios. One such example is for fast micro-payments. Zold is an experimental alternative that enables distributed transactions between anonymous users, making micro-payments financially feasible. It borrows the proof-of-work principle from Bitcoin, and suggests a different architecture for digital wallet maintenance.