Data Sources
How ShipMargin selects, verifies, and maintains shipping rule sources.
Last reviewed: August 31, 2026
Source priority
Sources are selected in this order.
- • Official carrier documentation
- • Official marketplace documentation
- • Government or postal authority
- • Verified API
- • Reliable secondary source
Verification states
Rules move through unverified, source_found, verified, and expired states. Only verified, currently effective rules can power production carrier calculations.
Current coverage
USPS Priority Mail commercial DIM rules effective July 12, 2026 are linked to the USPS Domestic Mail Manual. UPS and FedEx rules are marked REQUIRES_VERIFICATION in seed data and do not power production results.