CiviCRM - A Constituent relationship management for the Civic Sector
Avalara - Cut tax compliance costs, not corners. Avalara automates tax compliance and can help improve accuracy while reducing costs.
EspoCRM - EspoCRM is open source CRM (Customer Relationship Management) software that allows you to see, enter and evaluate all your company relationships regardless of the type.
TaxJar - TaxJar simplifies sales tax filing for eCommerce sellers.
Pipeliner CRM - Pipeliner CRM empowers small to medium-sized sales teams to close more deals and lower risk. Implementation and training are a breeze. Mac & Windows.
Thomson Reuters ONESOURCE - ONESOURCE tax software and solutions synchronize every aspect of your work and link international, country, state and local tax laws.