How do I get an API key?

Email support@bitpaypostage.com with your account email and a short description of your integration. Keys are issued per account and can be limited to specific permissions.

How are API labels paid for?

From your account's prepaid credit. The label cost is deducted before the label is created, and refunded automatically if the purchase fails. Top up the balance with Bitcoin, USDT, USDC or other supported coins, including through the API itself.

Can I resell labels through the API?

Yes. The API is built for resellers, shopping carts and marketplaces. You set your own price to your customers on top of the API rate.

Do I have to supply a return address?

Yes. Every label needs your own sender name, street, city, state and ZIP. The API never fills in a default return address.

Shipping label API for crypto businesses

The BitPayPostage API lets your store, marketplace or crypto checkout quote and buy USPS shipping labels in code. Labels are paid from prepaid account credit that you fund with Bitcoin, USDT, USDC or other coins, so you don't need a card on file or a monthly contract. It's a plain REST API at https://bitpaypostage.com/api/v1 that authenticates with an API key.

Request an API key →

Who it's for

Resellers who sell labels to their own customers and set their own price.
Shopping carts and marketplaces that need rates at checkout and a label when the order ships.
Crypto-native merchants who want to fund shipping from the same wallet their sales come in to.

Endpoints

Endpoint	Purpose
GET /status	Key details, permissions, monthly usage and current credit balance
POST /rates	Live shipping rates for a from/to address and package
POST /labels	Buy a label for a `rate_id`; returns the tracking number and label PDF
GET /labels	List labels bought with this key
GET /labels/:orderId	Look up a single label
POST /labels/:orderId/void	Void an unused label
POST /address/validate	Standardize and verify a shipping address
GET /credit	Current prepaid balance
POST /credit/topup	Create a crypto invoice to add credit
GET /transactions	Credit and label transaction history
GET /currencies	Cryptocurrencies accepted for top-ups

Quick start

Get rates for a 2 lb package:

curl https://bitpaypostage.com/api/v1/rates \
  -H "x-api-key: YOUR_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "from": {"name":"Your Store","street":"123 Main St","city":"Austin","state":"TX","zip":"78701"},
    "to":   {"name":"Customer","street":"456 Oak Ave","city":"Denver","state":"CO","zip":"80202"},
    "weight_lbs": 2, "length": 10, "width": 8, "height": 4
  }'

Then buy the rate you want with POST /labels, passing the rate_id and the same from address. The label cost is deducted from your credit before the label is created, and refunded automatically if the purchase fails.

Billing

Pay before label. Every label is paid from prepaid credit at the moment you buy it, so there are no invoices to chase.
Fund with crypto. Top up with Bitcoin, Litecoin, Ethereum, Solana, USDT or USDC, Monero or Zcash, from the dashboard or with POST /credit/topup.
Per-key limits. Each key has its own rate limit, monthly label limit and permission set.

Frequently asked questions

How do I get an API key?: Email support@bitpaypostage.com with your account email and a short description of your integration. Keys are issued per account and can be limited to specific permissions.
How are API labels paid for?: From your account's prepaid credit. The label cost is deducted before the label is created, and refunded automatically if the purchase fails. Top up the balance with Bitcoin, USDT, USDC or other supported coins, including through the API itself.
Can I resell labels through the API?: Yes. The API is built for resellers, shopping carts and marketplaces. You set your own price to your customers on top of the API rate.
Do I have to supply a return address?: Yes. Every label needs your own sender name, street, city, state and ZIP. The API never fills in a default return address.