Postmen API
Postmen (now AfterShip Shipping) is an API-first product: REST endpoints for rates, labels, manifests, pickups, and address validation with SDKs in six languages. API keys are self-serve and the API itself is free; volume and dashboard features sit on paid plans.
Frequently asked questions
Postmen scores A on the API Report Card. Postmen (now AfterShip Shipping) is an API-first product: REST endpoints for rates, labels, manifests, pickups, and address validation with SDKs in six languages. API keys are self-serve and the API itself is free; volume and dashboard features sit on paid plans.
Postmen has a workable official integration path. Most engineering teams can build against it directly. Open API: self-serve, documented, with SDKs
Postmen is a multi-carrier shipping API from AfterShip, the same Hong Kong-headquartered company behind the AfterShip post-purchase tracking platform, that gives developers a single REST interface for calculating live shipping rates, generating labels and customs documents, scheduling pickups, transmitting end-of-day manifests, and validating addresses across 100+ couriers.
Primary vertical: Fleet / Trucking / Logistics, specifically the multi-carrier shipping abstraction layer used by ecommerce platforms, marketplaces, 3PLs, ERP/OMS vendors, and direct-to-consumer brands that need to print labels and rate-shop across UPS, FedEx, USPS, DHL, TNT, Canada Post, Australia Post, Royal Mail, DPD, GLS, China Post, SF Express, and regional carriers without negotiating individual API contracts with each one. A Shopify-based DTC brand or a custom storefront calls POST /rates with origin, destination, package weight, and dimensions to retrieve live rates from every connected carrier account, picks the cheapest qualifying service, then calls POST /labels to generate a PDF/PNG/ZPL label and tracking number in a single request.
Moderate-to-high within the developer-shipping niche.
Postmen sits directly in the fulfillment critical path: every label generated represents a customer order that must ship today, and every failed /rates call shows up as missing shipping options at checkout that drive cart abandonment.
Postmen launched around 2014–2015 as AfterShip's developer-facing shipping API, predating the broader ShipEngine and Shippo product launches in the same space.
Grades measure one thing: can a customer's engineering team get their own data out programmatically? We check six things (whether a real API exists, how access is gated, data coverage, auth quality, docs and developer experience, and stability) and roll them into a letter grade. Grades get re-verified, and they only move on evidence.