Sales Tax Clearinghouse
Offering online state sales tax returns.
http://thestc.com/

Independent Systems
Specializes in tax software and databases. Online internet sales tax rate query is available for direct or web based users.
http://www.taxrates.com/

Taxware International
Provide solutions for Sales, Use, and Consumer's Use taxes as well as worldwide VAT.
http://www.taxware.com/

Sabrix, Inc.
Provider of TaxBay, a global transaction tax calculation and management software package.
http://www.sabrix.com/

Aptax ZipTax
Windows-based sales tax preparation software for the state of California.
http://www.ziptax.com/

Kamp Data DynamicZip
Provides sales tax calculations and creates and maintains sales tax schedules for all United States jurisdictions.
http://www.kampdata.com/

Electronic Sales and Use Tax, Inc.
Sales Tax filing software for California and Florida.
http://www.efilesalestax.com/

SalesTax-Pro
California sales tax preparation that integrates with QuickBooks data. Offered in English or Spanish.
http://www.salestax-pro.com/

Tax Data Systems
Sells sales and use tax databases for the United States.
http://www.taxdatasystems.com/

CCH Group
Offers general tax rates and forms by ZIP code, covering the United States, Territories, and Canada.
http://tax.cchgroup.com/

Front Row Systems, Inc.
Sales and use tax management software providing a full range of sales tax automation features.
http://www.frontrowsystems.com

Avalara Sales Tax Software
State sales tax and use tax calculator for tax calculation, and address verification and validation for accounting software, such as Great Plains, ACCPAC, MAS 90 and MAS 200.
http://www.avalara.com

AlternaDev
Sales and Use Tax Compliance services and software. AlternaDev manages tax compliance with our branded software AlternaTax, which automates the returns process to save time and money.
http://www.alternadev.com/