Data sources

Each calculator on BuildStack shows its own as-of date on the tool page itself. This page collects all seven in one place, states plainly which tools use real official data versus a placeholder, and explains which tools don't depend on external data at all.

Tools backed by real, sourced data

Tariff & Customs Calculator

General (MFN) duty rates come from the official USITC Harmonized Tariff Schedule, 2026 Revision 2 — as of 2026-08-24. Only entries with a plain ad-valorem rate are included; entries with compound or specific duties are excluded rather than approximated. See MFN tariffs vs. additional tariffs for what this rate does and doesn't cover.

Landed Cost Calculator

Standard EU VAT rates come from eu-vat-rates-data, an MIT-licensed dataset checked against the European Commission's Taxes in Europe Database (TEDB) — as of 2026-08-24. Duty is a user-supplied flat amount, not looked up, since there's no free bulk EU duty (TARIC) dataset available.

Visa & Passport Photo Resizer

Photo specs are drawn from official government and treaty sources, each cited on its own line:

• US — U.S. Department of State (travel.state.gov): 2×2 in, head height 1–1⅜ in. Confirmed 2026-08-24.
• UK — HM Passport Office (gov.uk): 35×45mm, chin-to-crown 29–34mm. Confirmed 2026-08-24.
• Schengen — EU Visas Code (Regulation 810/2009) + ICAO Doc 9303: 35×45mm, head height 32–36mm. Confirmed 2026-08-24.
• Canada — IRCC (canada.ca): 50×70mm, head height 31–36mm. Confirmed 2026-08-24.
• Japan — unverified: sources conflict between 45×45mm and 35×45mm specs. Flagged in the tool's UI with an amber warning; confirm with the specific consulate before use.

Tools that use placeholder data

International Shipping Cost Comparator

Carrier names and per-kg rates are illustrative placeholders, last updated 2026-08-01 — not a live quote from any real carrier. There's no free, public, multi-carrier rate comparison source available; each carrier's own API needs a separate business account and only returns that carrier's own rates. Use this tool to understand how dimensional weight affects cost, not to book a real shipment.

Tools with no external data dependency

These tools don't look anything up — their logic is entirely self-contained code, so there's no "as of" date that applies:

• Label & Barcode Sheet Generator — Avery 5160 grid geometry is a fixed, published template specification, not fetched data.
• PDF Editor & Signer — merge/split/rotate/watermark/ sign operations run entirely through the pdf-lib library on whatever PDF you upload; there's no reference dataset involved.
• EPUB Format Checker — validates structure against the EPUB specification's own requirements (packaging, required metadata, manifest/spine integrity, cover declaration, navigation document), not against any external or changing dataset.

Questions about a specific number or source? See the Contact page.