Quickstart

This guide gets you up and running with the Synapto API: verify your credentials, make your first API call, then choose the integration path that fits your use case.

All amounts are in the smallest currency unit (e.g. pence for GBP, cents for USD).

Prerequisites

• A Synapto account — sign up at dashboard.synaptopay.com (or dashboard.synapto.construction for sandbox)
• An API key — create one in Settings > Developer (see Authentication)
• Your account ID — visible in the Dashboard URL (e.g. acct_RwDJsJd8z0exhtfX2570Q)

Resource names

The Synapto API uses resource names to identify objects. Rather than passing bare IDs, you pass the full resource path:

accounts/acct_RwDJsJd8z0exhtfX2570Q/customers/cus_oRlM8p6VQ57xxmRhQ9sQc

These resource names are returned in the name field of every API response, and you pass them back to the API when referencing that resource.

Make your first API call

Verify your API key works by retrieving your account:

curl https://api.synaptopay.com/v1/accounts/acct_YOUR_ACCOUNT \
  -H "Authorization: Api-Key sk_live_YOUR_API_KEY"

If you see your account details in the response, you're ready to go.

Choose your integration

Checkout sessions — hosted payment page

The fastest way to collect payments. Create a session and redirect your customer to a Synapto-hosted payment page. No frontend code required. The Idempotency-Key header lets you safely retry requests — see Idempotency.

curl -X POST https://api.synaptopay.com/v1/accounts/acct_YOUR_ACCOUNT/checkout-sessions \
  -H "Authorization: Api-Key $API_KEY" \
  -H "Idempotency-Key: YOUR_UNIQUE_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "amount": "10000",
    "currency": "GBP",
    "success_url": "https://example.com/success"
  }'

The response includes a url — send your customer there to pay.

See Checkout Sessions for the full guide.

Payment intents + JS SDK — custom payment form

For full control over the payment experience, use payment intents with the JS SDK to build your own checkout. This lets you save cards, charge them later, and handle 3D Secure in your own UI.

See Taking Payments and JS SDK to get started.

Invoices — bill customers directly

Create invoices with line items and send them to customers for payment.

See Invoices for the full guide.

Next steps

• Authentication — API keys, environments, and base URLs
• Customers — creating and managing customers
• Standalone Accounts — creating sub-accounts under your platform
• Saving Cards — securely storing customer payment methods
• Refunds — returning funds to customers
• Webhooks — receiving event notifications
• Idempotency — safely retrying requests
• Error Handling — error codes and payment decline codes
• Testing — sandbox simulations for settlements and payouts
• API Reference — full endpoint documentation

Support

If you need any help, reach out to [email protected], mention you are an engineer and someone technical will get back to you.

Before go-live, escalation paths (e-mail, phone, etc.) are shared.