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.

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

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.

[Deprecated] The PayPal REST SDK provides Ruby APIs to create, process and manage payment. It is recommended to use paypal-server-sdk instead

Quickly build an online store with carts, orders, automatic email receipts and payment collection via Stripe, StripeConnect, PayPal and Moneris.

The Authorize.Net Ruby SDK is meant to offer an alternate object-oriented model of development with the Authorize.net APIs (Version 3.1). The SDK is based entirely off the name-value pair API, but performs the core payment activities (such as error handling/parsing, network communication, and data encoding) behind the scenes. Providing the end developer with this allows the developer to start integrating immediately without having to write out a mass of boiler plate code.

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.

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

[Deprecated] It is recommended to use paypal-server-sdk instead 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.

Balanced is the payments platform for marketplaces.

Radiant Shop is an attempt at a simple but complete store. It includes Products, Categories, Orders and Credit Card Payments

WebPay is payment gateway service in Japan. See also https://webpay.jp/.

Base gateway for Unlock's payment gateway integrations

Simplifies generating payment requests and parsing responses from banks when using iPizza protocol.

[Deprecated] It is recommended to use paypal-server-sdk instead. The PayPal Permission SDK provides Ruby APIs for developers to request and obtain permissions from merchants and consumers, to execute APIs on behalf of them. The permissions include variety of operations from processing payments to accessing account transaction history

An rails plugin that provides a fake framework to stub 3-party redirect page such as payment or oauth login.

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.

A Ruby gem wrapper for the pin-payments (pinpayments.com) API

The CompassAE Commerce Engine uses the engines that implement Parties, Products and Orders, and adds the ability to conduct commerce. It implements a pricing engine, fees, payment gateways.