Drop Zone is a solution to the problem of restricted sales in censored markets. The proposal is for the design of a protocol and reference client that encodes the location and a brief description of a good onto The Blockchain. Those wishing to purchase the good can search for items within a user-requested radius. Sellers list a good as available within a geographic region, subject to some degree of precision, for the purpose of obfuscating their precise location. Goods are announced next to an expiration, a hashtag, and if space permits, a description. Once a buyer finds a good in a defined relative proximity, a secure communication channel is opened between the parties on the Bitcoin test network ("testnet"). Once negotiations are complete, the buyer sends payment to the seller via the address listed on the Bitcoin mainnet. This spend action establishes reputation for the buyer, and potentially for the seller. Once paid, the seller is to furnish the exact GPS coordinates of the good to the buyer (alongside a small note such as "Check in the crevice of the tree"). When the buyer successfully picks up the item at the specified location, the buyer then issues a receipt with a note by spending flake to the address of the original post. In this way, sellers receive a reputation score. The solution is akin to that of Craigslist.org or Uber, but is distributed and as such provides nearly risk-free terms to contraband sellers, and drastically reduced risk to contraband buyers.

Experimental library for working with GoogleCheckout. Currently in use for payment at http://peepcode.com.

A straight-forward REST API for Amazon's Flexible Payments Services.

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

Spreedly is a cloud service that allows you to store credit cards and run transactions against them, enabling you to accept payments on your website while avoiding all liability and PCI compliance requirements.

Easy online payments with eWAY and the eWAY Rapid Ruby gem.

Robokassa is payment system, that provides a single simple interface for payment systems popular in Russia. If you have customers in Russia you can use the gem. The first thing about this gem, is that it was oribinally designed for spree commerce. So keep it in mind.

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

Spree extension for integration with PayPal Website Standard payment

Add wallet payment method functionality to spree

[Deprecated] 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

This is currently a dummy until a public beta is over.

TrueLayer provides instant access to open banking to easily integrate next-generation payments and financial data into any app.This helps easily sign TrueLayer API requests using a JSON web signature.

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

A Ruby gem for communicating with the payment platform of Redsys

[Deprecated] The PayPal Adaptive Payments SDK provides Ruby APIs to create, process and manage simple and complex (parallel and chained) payments, and pre-approvals using the Adaptive Payments API.

Implementation of Loan/Mortgage functions in Ruby language. APR function and PMT function. In calculations it includes implementation of bank fee, marketplace fee, fees for each payment to provide the most precise calculation at very high speed.

Payment Method for Skrill Transactions for Spree

iDEAL payment gateway (see http://www.ideal.nl and http://www.activemerchant.org/)

A library to interface with Fawry's payment gateway API (charge, refund, payment status, service callback).