ChargeOver - ChargeOver automates recurring billing, subscription billing, & payment acceptance. A SaaS that integrates with Xero, Quickbooks, & has an API. Free trial.
Pabbly Subscriptions - Pabbly Subscription is a recurring billing & subscription management software.
Elorus - A super-easy online invoicing & time tracking software
Recurly - Subscription billing and recurring billing management. Recurly offers enterprise-class subscription billing for thousands of companies worldwide.
MinuteDock - Web-based time tracking software designed to integrate with the Xero accounting package.
Chargebee - Chargebee lets you manage subscriptions and payments at scale, handle custom recurring billing scenarios, reduce subscription churn and simplify accounting.