Developer builds free tool to flag USPS hazmat fees before shippers buy labels
USPS can retroactively charge shippers a $50 hazardous materials noncompliance fee after a package has already been delivered, with no prior warning at the counter. A developer discovered the fee rules are spread across conflicting official documents — including Federal Register notices, Industry Alerts, and Postal Bulletins — that most sellers would never think to consult. In response, they built CanWeShip, a free pre-shipping compliance checker that lets users select a product type and receive side-by-side USPS, UPS, and FedEx verdicts with cited official sources. Unlike AI chatbots, the tool uses a deterministic rule engine backed by versioned, traceable rule sets, and explicitly flags gaps in information rather than guessing. A separate rule update also notes that USPS Returns shipments will become subject to the fee starting February 1, 2027.







