eBay Enterprise - eBay Enterprise provides a variety of marketing, customer care, payment processing, fulfillment, fraud detection services.

ChargeOver - ChargeOver automates recurring billing, subscription billing, & payment acceptance. A SaaS that integrates with Xero, Quickbooks, & has an API. Free trial.

Sellbery - Easily automate product feeds from Shopify, Magento to Amazon, eBay and other marketplaces. Fully utilize the most profitable eCommerce channels and increase sales.

fusebill - Fusebill is the leading recurring billing and subscription management software for businesses. Try Fusebill for subscription billing made easy!

Radial - Radial offers order management and store fulfillment solutions.

MinuteDock - Web-based time tracking software designed to integrate with the Xero accounting package.