API Checkout Flow

Server-to-server integration — from checkout creation to webhook delivery.

Flow Overview

This diagram shows the full developer integration using the SatsRail REST API. The merchant's backend creates checkout sessions server-side using the secret key ( sk_live_ ), redirects customers to the hosted checkout page, and receives payment confirmations via signed webhooks. Funds settle directly to the merchant's Lightning wallet (non-custodial).

Action
Success
Error
Data
Security
Decision Point
→ Flow Direction

Sequence Diagram

API Endpoints

Method Endpoint Description Auth
POST /api/v1/checkout_sessions Create a new checkout session sk_live_
GET /api/v1/checkout_sessions/{id} Retrieve checkout status sk_live_
GET /api/v1/m/products List all products sk_live_
POST /api/v1/m/products Create a product sk_live_
GET /api/v1/transactions List transactions with filters sk_live_
GET /api/v1/rates Current BTC/USD exchange rate pk_live_ or sk_live_

Step-by-Step Detail

Phase 1: Setup & Authentication

1
Obtain API Keys

Merchant registers on SatsRail and receives two API keys:

  • pk_live_... — Publishable key (safe for client-side/frontend)
  • sk_live_... — Secret key (server-side only, never exposed to clients)
The secret key must never be included in frontend code, committed to version control, or exposed in client-side requests.
2
Connect Wallet & Configure Webhook

Connect a Lightning wallet via the Dashboard or API. Configure a webhook endpoint URL where SatsRail will send payment event notifications.

Phase 2: Checkout Creation

3
Customer Initiates Checkout

Customer adds items to cart on the merchant's frontend, clicks "Checkout with Bitcoin." The frontend sends cart data to the merchant's backend server.

4
Backend Creates Checkout Session

Merchant backend sends a POST request to SatsRail:

POST /api/v1/checkout_sessions
Authorization: Bearer sk_live_...
Content-Type: application/json

{
  "checkout_session": {
    "amount_cents": 5000,
    "currency": "usd",
    "customer_email": "buyer@example.com",
    "success_url": "https://store.com/success",
    "cancel_url": "https://store.com/cart",
    "metadata": { "order_id": "ORD-1234" }
  }
}

SatsRail validates the secret key, checks rate limits, validates the payload schema, then creates a CheckoutSession with a 15-minute TTL.

5
Redirect Customer

SatsRail returns:

{
  "checkout_url": "https://satsrail.com/checkout/cs_abc123",
  "token": "cs_abc123",
  "status": "pending",
  "expires_at": "2024-01-15T10:15:00Z"
}

The merchant backend returns the checkout_url to the frontend, which redirects the customer to the SatsRail hosted checkout page.

Phase 3: Payment Execution

6
Checkout Page & Payment

The SatsRail checkout page shows line items, total in USD and sats, and generates a Lightning invoice from the merchant's wallet (non-custodial). Customer pays via QR scan, copy, or WebLN.

Payment routes through Lightning and settles instantly to the merchant's wallet.

Phase 4: Post-Payment & Webhooks

7
Webhook Delivery

SatsRail sends a POST to the merchant's webhook endpoint:

POST https://merchant.com/webhooks/satsrail
X-SatsRail-Signature: sha256=abc123...

{
  "event": "checkout.completed",
  "checkout_id": "cs_abc123",
  "payment_hash": "abc123...",
  "amount_sats": 50000,
  "amount_usd": "50.00",
  "metadata": { "order_id": "ORD-1234" },
  "timestamp": "2024-01-15T10:02:30Z"
}

The merchant verifies the HMAC signature using their webhook secret, processes the order, and returns 200 OK. On failure, SatsRail retries: 1 min → 5 min → 30 min → 2 hr.

8
Client-Side Confirmation

Customer is redirected to the merchant's success_url with checkout_id as a query param. The merchant frontend calls GET /api/v1/checkout_sessions/{checkout_id} to verify the status is "completed" before showing the success page. Never trust the redirect alone — always verify server-side.

Error Paths

HTTP Status Error Trigger Recovery
401 Unauthorized Invalid or missing API key Check sk_live_ key in Authorization header
422 Validation Error Malformed payload, missing required fields Check field-level error messages in response body
429 Rate Limited Too many requests per minute Implement backoff; check Retry-After header
410 Gone Checkout session expired (15 min TTL) Create a new checkout session
200 Double Payment Idempotency check detects existing payment Returns existing payment record (no double-charge)
5xx Webhook Failure Merchant endpoint unreachable or returns error SatsRail retries: 1 min → 5 min → 30 min → 2 hr

Build your custom checkout

One API call to create a checkout. Lightning settlement. Webhook confirmation.

Checkout API Docs → Webhooks Docs →