# foomworks — Tariff & Duty Tools

> Current US import duty (tariff) data for any Harmonized Tariff Schedule (HTS) code: base/MFN rate, Section 301/232/122 surcharges, MPF/HMF, and a maintained log of what changed. Rebuilt from the official USITC schedule about every 30 minutes. Part of foomworks (https://foomworks.app).

## Free, human-readable & indexable pages
- https://duty-stack.foomworks.workers.dev/tariff — overview + popular codes
- https://duty-stack.foomworks.workers.dev/tariff/{code} — current duty for one HTS code (example: https://duty-stack.foomworks.workers.dev/tariff/6109.10.00.12)
- https://duty-stack.foomworks.workers.dev/tariff/chapter/{nn} — every rate-bearing code in an HTS chapter
- https://duty-stack.foomworks.workers.dev/tariff/changes — newest-first change log (revisions, surcharges, per-code rate moves)
- https://duty-stack.foomworks.workers.dev/sitemap.xml — all indexable pages

## JSON API for agents (pay-per-call via x402, USDC on Base, no account)
- GET https://duty-stack.foomworks.workers.dev/duty?code={code}&origin={iso2}&value={usd} — full landed-cost duty stack (base + 301/232/122 + MPF/HMF) + FTA preferential eligibility by origin (USMCA/KORUS/CAFTA-DR/…). $0.05
- GET https://duty-stack.foomworks.workers.dev/hts/lookup?code={code} — normalized rate line (rates, footnotes, Chapter 99 refs). $0.03
- GET https://duty-stack.foomworks.workers.dev/hts/search?q={keyword} — find HTS codes by keyword. $0.02
- GET https://duty-stack.foomworks.workers.dev/changes — full machine-readable change feed. $0.02
Paid endpoints return an HTTP 402 challenge (x402 protocol, https://x402.org); pay and retry to receive JSON.

## Free API
- GET https://duty-stack.foomworks.workers.dev/duty/preview?code={code} — heading-level duty preview
- GET https://duty-stack.foomworks.workers.dev/hts/search/preview?q={keyword} — keyword search preview
- GET https://duty-stack.foomworks.workers.dev/changes/by-code?codes={a,b} — recorded changes for your own codes
- GET https://duty-stack.foomworks.workers.dev/health — status · GET https://duty-stack.foomworks.workers.dev/stats — usage counters

## Alerts for humans
- https://duty-stack.foomworks.workers.dev/watch — free email alerts when the duty picture changes for codes you import

Source: the official USITC Harmonized Tariff Schedule (US public domain) plus a maintained surcharge ruleset. Informational only — not customs, legal, or financial advice.