API quickstart

Create an API key and send a customer to checkout in a few minutes.

This walkthrough takes you from a fresh store to a working checkout link using a single API call.

Create an API key

In the dashboard, open Developers → API Keys and create a key with the checkout_api permission. Copy it right away - it starts with sk_ and is only shown once.

Store the key on your server

Keep the key in an environment variable on your backend. It must never ship to a browser or mobile app.

.env

PAYSUM_API_KEY=sk_your_secret_key

Create a checkout session

Send the items you want to charge for. The response contains a hosted checkout URL.

curl -X POST "https://paysum.io/api/checkout-api/sessions" \
  -H "Authorization: Bearer $PAYSUM_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "line_items": [{ "name": "Premium License", "price": 29.99, "quantity": 1 }],
    "success_url": "https://example.com/success"
  }'

Redirect the customer

Send the customer to the returned url. After paying they land on your success_url. To fulfil orders reliably, listen for the checkout.session.completed webhook rather than relying on the redirect.