Shiplines

Shipline is a fast offline shipping rate comparer for solo sellers. Enter a parcel - weight, dimensions, from-ZIP, to-ZIP - and instantly see what USPS, UPS, and FedEx will charge for the same shipment. No accounts, no scraping, no login.

Designed for Etsy, eBay, Mercari, Poshmark, and Depop sellers who pack their own packages and want a per-shipment answer in under five seconds, not a quote workflow.

WHAT SHIPLINE COMPARES

• USPS Priority Mail
• USPS Ground Advantage
• UPS Ground
• FedEx Ground

EACH RESULT SHOWS

• The price for that carrier, ranked cheapest first
• Dollars saved by the cheapest option vs the next-best option
• Estimated delivery window (business days)
• The zone the calculation used
• Whether dimensional weight beat the actual weight

HOW SHIPLINE WORKS

• 3-digit ZIP prefix centroids and distance bands map the route to a USPS-style zone 1-9
• Per-carrier dim divisors (USPS 166, UPS 139, FedEx 139) apply when box volume wins
• USPS Priority and Ground Advantage bill in ounces under a pound; UPS and FedEx Ground round up to the next whole pound
• All four pricings happen on this device against a baked-in 2026 reference table - no network call

WHAT'S INCLUDED

• Calculator tab with parcel template loader
• Saved parcels - reusable weight + dim + route templates
• History - last 30 quotes kept locally
• Settings - default origin ZIP, weight unit preference, dimension unit preference, haptics toggle, More apps by Robert Corbin link

PRIVATE BY DESIGN Shipline has no account, no ads, no analytics, no tracking, no subscription, and no developer backend. Saved parcels and history live in local app storage. There is no network access of any kind.

ESTIMATES ONLY Rates are baked-in approximations from public 2026 published retail tables. A Disclaimer banner appears on every comparison reminding you to verify pricing with the carrier before purchasing labels.

Shipline is a one-time paid utility for sellers who want the same-axis carrier answer without paying for an account or pulling out a calculator.