Open Source Projects
The tariff engine and data behind Invoice × Tariff are open source: the same versioned ruleset snapshot drives this site's calculators and ships as an npm package, a browser extension and open datasets you can integrate freely. Everything is MIT licensed.
npm package
Our tariff engine packaged as a zero-dependency TypeScript library + CLI: calculateLandedCost, searchHts, changelogEntries and more. The ruleset snapshot ships inside the package and updates monthly, in lockstep with this site. On the command line: npx us-tariff calc / search / meta.npm install us-tariff-lookup
GitHub repositories
Source repository for the us-tariff-lookup npm package: engine bundling, CLI and release pipeline.
Source repository for the “US Tariff Lookup” browser extension: one Manifest V3 codebase for Chrome, Edge and Firefox. Look up HTS codes and stacked duty rates from the toolbar; data is bundled and works offline.
US Tariff Lookup desktop app (Electron): offline lookup and landed-cost calculation for Windows / macOS / Linux — same engine as the web calculator. Desktop app
Browser extension
“US Tariff Lookup” is live on Microsoft Edge Add-ons: look up HTS codes, MFN duty rates and stacked Section 301/232 layers from the toolbar; data is bundled and works offline.
The Firefox Add-ons (AMO) and Chrome Web Store versions are under review — links will be added here once approved.
Open data
A machine-readable CSV dataset of duty rates for 475 high-frequency HTS codes (MFN + Section 301 China + Section 232) is published under CC BY 4.0, from the same ruleset snapshot the engine uses. Tariff data — for Excel, Python and Sheets usage see the Tutorials.
All projects above are open source under the MIT license — issues and PRs welcome.