TaxJar - TaxJar simplifies sales tax filing for eCommerce sellers.
BillGrid.com - BillGrid is an easy to use online invoicing, billing and expense management system that will save you time with tracking clients projects, expenses, invoices and payments.
Thomson Reuters ONESOURCE - ONESOURCE tax software and solutions synchronize every aspect of your work and link international, country, state and local tax laws.
ChargeOver - ChargeOver automates recurring billing, subscription billing, & payment acceptance. A SaaS that integrates with Xero, Quickbooks, & has an API. Free trial.
Vertex Cloud - Vertex Cloud offers sales and use tax automation solutions.
MinuteDock - Web-based time tracking software designed to integrate with the Xero accounting package.