The shipping API your
storefront actually wants.
Quote multi-carrier rates, buy + refund labels, and subscribe to shipment events from any backend. JSON in and out, bearer-token auth, flat $0.08 per label.
- Bearer-token auth + scopes
- Signed webhook deliveries
- $0.08 per label, no monthly fee
$ curl -X POST shiponline.app/api/v1/labels/create \
-H "Authorization: Bearer shp_live_…" \
-d '{
"fromAddress": { "zip": "94103", ... },
"toAddress": { "zip": "10001", ... },
"parcel": { "lengthIn": 10, ... },
"serviceCategory": "standard"
}'{
"id": "cm123abc",
"status": "purchased",
"carrier": "USPS",
"service": "Priority",
"trackingCode": "9405511…",
"labelUrl": "https://…/cm123abc.pdf",
"chargeAmountCents": 695
}API reference
Everything you need to ship.
Eleven focused pages covering the full API — from the three-minute quick-start to webhook signature verification and rate-limit backoff. Pick any topic to dive in; each page stands alone.
Getting started
Resources
Rates
Quote multi-carrier rates. Smart-rate categorization, international quoting, 5-min cache.
Read moreLabels
Create, get, list, refund. Idempotency-keyed buys, async carrier processing, full lifecycle.
Read moreTrackers
Carrier tracking events auto-attach to every label. Latest scan + full history.
Read moreAddresses
Verify + standardise before quoting. Residential vs commercial detection, international support.
Read more
Reference
Webhooks
Subscribe to events with HMAC-SHA256 signatures + replay protection.
Read moreErrors
Every HTTP code, error body shape, retry semantics, idempotency edge cases.
Read morePagination
Cursor-based pagination. Iterate to completion with stable ordering.
Read moreRate limits
Token-bucket limits per endpoint, 429 + Retry-After semantics, backoff guidance.
Read moreChangelog
Versioning policy + every change. Old versions live for at least 12 months past sunset.
Read more