universal-checkoutlisted

# 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](https://www.zinc.com/docs/v2/agent-sandbox/quickstart.md) and [Going Live](https://www.zinc.com/docs/v2/agent-sandbox/going-live.md). 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 `