Independent analysis

How To Integrate CoinPayments API

The CoinPayments API is a REST JSON interface merchants can use to create invoices, read rates, inspect fees, and receive webhook updates for crypto payments.

Integration Plan

Start by confirming your account's production API instance. Official documentation notes that CoinPayments can operate multiple production API domains, so code should not assume every account uses the same base URL.

Authentication

Authenticated requests use HMAC SHA-256 signatures. Build a small test harness that signs a fixed payload, timestamp, method, and URL before you connect checkout code. Most integration failures we expect are not conceptual; they are byte-level mismatches in signed strings.

Invoices

Use invoice creation for checkout sessions and store your internal order ID alongside the gateway invoice ID. A merchant should update an order only after receiving and verifying a webhook or polling confirmed invoice status.

Webhooks

Webhook handlers must be idempotent. The same event can arrive twice, arrive late, or arrive after a customer has contacted support. Store raw event IDs, timestamps, and resulting state transitions.

Testing Checklist

1. Create a sandbox or low-value test invoice.
2. Verify callback signature handling.
3. Test underpayment, overpayment, and expired invoice handling.
4. Confirm finance exports match order records.
5. Rotate credentials before production if test secrets were shared broadly.

Sources

• CoinPayments API Documentation for platform, API domain, HMAC authentication, rate limits, and v2/legacy notes.
• CoinPayments Fees for public processing fee language.
• CoinPayments Supported Coins for new-platform coin and payment support claims.
• CoinPayments Rates API for rate endpoint details.