ONESOURCE Determination vs OpenSalesTax

ONESOURCE Determination automates calculations for sales tax, use tax, GST, VAT, and excise tax. The web-based product connects with ERP, financial, billing, e-commerce, point-of-sale, and payment systems through pre-built or custom integrations. It supplies global tax rates, rules, and calculations in real time, with cloud synchronization to support high transaction volumes. Deployment includes a cloud-based indirect-tax engine and an edge-computing option. Determination Anywhere supports business-specific security and data-residency requirements. Tax content covers specialized jurisdictions and industries, with industry offerings for oil and gas, retail, manufacturing, and technology. Configuration features include company structures, global calculations, and tax-return streamlining. Thomson Reuters says its automated calculations and certified processes aim to reduce audit-triggering mistakes; the processes are backed by SSAE 18 and ISAE 3402 certifications. Pricing is on request, and a free demo can be requested.

OpenSalesTax is a free, self-hosted API that calculates sales tax for US transactions using public data and per-state modules. The project says its modules cover 52 jurisdictions, while each published data dump includes all 48 jurisdictions that impose sales tax. The API calculates tax on line items and can break results down by state, county, city, or district. Documented item categories include general goods, clothing, groceries, prescription drugs, prepared food, and digital goods. Its data comes from Streamlined Sales Tax files and state Department of Revenue publications, rather than paid tax feeds. The engine can be installed from source or run with Docker; PostgreSQL is the default, with optional MariaDB support. Access defaults to open with per-IP rate limiting, or can use API keys with per-key limits and usage tracking. Release dumps reflect the SST quarterly file current at release, and the project documents loading newer data. It identifies incomplete sub-state tax stacking for Colorado home-rule cities and Louisiana parish-level collectors. The project says its calculations are not legal or tax advice and advises checking results with the relevant state Department of Revenue before remitting.