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name: universal-checkout description: Discover, buy, track, and return real products from Amazon, Walmart, Target and almost any other US online retailer through the Zinc API (zinc.com). Needs no account to begin — the agent mints its own test key, then earns a live key and a $5 starter credit once its operator approves it. Pay from a pre-funded wallet, per request over MPP or x402, or with a Stripe Link card.

Universal Checkout

One API to discover, buy, track and return products from US online retailers. Base URL https://api.zinc.com.

Which retailers

Pass a product URL from almost any US retailer — an uncatalogued domain is first class on the order path, and in a recent 60-day window customers ordered from 296 distinct domains. GET /retailers (free, no auth) lists the storefronts with published guarantees: free-shipping terms, whether an account is needed, where they ship. Check it when those details matter.

Getting started

Four steps, in order. Full walkthrough: Agent Sandbox Quickstart and Going Live.

1. Get a test key. POST https://api.zinc.com/sandbox/keys — no auth, no signup. Returns api_key (zn_test_…) and a ready-made example_order. Send it as Authorization: Bearer <api_key> from here on.
2. Place a test order. POST /orders with that example_order, then poll GET /orders/{id}. Free. status reaches order_placed — that is success, and it never becomes delivered; shipping shows up under tracking_numbers[0].status.
3. Earn your live key. POST /device/code with your test key as Bearer — that is what carries your sandbox history over. Show your operator the link it returns, then poll POST /device/token (no Authorization header; 400 authorization_pending means keep waiting). On approval you get a zn_live_ key once, plus a $5 starter credit in their wallet.
4. Buy something real. Walmart orders usually ship free — reliably from about $10; below that shipping is often added, so a very cheap item can cost more delivered than it looks. Search with GET /search?q=<item>&retailer=walmart to get Walmart results only. max_price is a ceiling, not a price: you are charged the retailer's actual total, so leave room for tax and shipping. Ask your operator for the shipping address (phone_number is required) and confirm the item and price with them first.

Watch the money: GET /wallet/me shows the balance and order_fee_cents (charged per order, on top of max_price). Each /search call costs 1¢ from the same wallet.

Already have a key from your operator? Use it and skip to Place an order. Never want an account? Pay per request over MPP: POST /agent/orders, no key needed.

Place an order

curl -X POST https://api.zinc.com/orders \
  -H "Authorization: Bearer $ZINC_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "products": [{"url": "https://www.amazon.com/dp/B09V3KXJPB", "quantity": 1}],
    "max_price": 5000,
    "shipping_address": {
      "first_name": "Jane", "last_name": "Doe",
      "address_line1": "123 Main St", "city": "San Francisco",
      "state": "CA", "postal_code": "94105", "country": "US",
      "phone_number": "4155552671"
    }
  }'

• max_price is the ceiling in cents for the whole order. Zinc refuses rather than exceeding it.
• phone_number is required. Never invent an address — ask your operator.
• To buy on your operator's own Zinc Universal Checkout account, pass its short_id as retailer_credentials_id (GET /managed-accounts lists them). The payment method saved on that account pays the retailer, and the wallet is charged the per-order fee only. Omitting the field never means "pick one of mine" — it means the order runs on a Zinc account and the wallet pays for the item. (retailer accounts)
• Returns 201 with an order id and status: pending. Retailer, variants, quantities, gift options, idempotency: Create Order.

Track, cancel, return

• GET /orders/{id} — status is one of pending, order_placed (success), order_failed, cancelled. Shipping lives on tracking_numbers[].status. (statuses, tracking)
• POST /orders/{id}/cancel — only while pending. (cancel)
• POST /returns — needs the order id and a reason. (returns)

When something fails

Errors are {"error": {"code", "message", "details"}}. Read code, not the message. details often names the fix — a 402 insufficient_funds carries fund_with, every way to pay, including your operator's own retailer account when they have one saved for that store. Full list: Error Handling and references/errors.md.

Rules

• Money is real. Confirm the item and the price with your operator before any live order.
• Set max_price deliberately — it is the only thing standing between a typo and a large purchase.
• Never invent a shipping address, and never reuse the sandbox one for a live order.
• Rehearse failures in the sandbox first: GET /orders/test-products.

All amounts are in US cents (e.g. 5000 = $50.00). US delivery.