Create a Cost+ account, test your first payment in a sandbox website, and prepare your integration for live payments.
Before you start
You need:
- Access to the Cost+ Merchant Portal
- A server-side application or a supported eCommerce platform
- A safe place to store API keys outside client-side code and public repositories
1. Create your account
Create a Cost+ account, then sign in to the Merchant Portal. The portal is where you manage websites, payment methods, API credentials, transactions, and webhooks.
2. Create a sandbox website
In the Merchant Portal, open Websites and create a sandbox website. A sandbox website lets you test without moving real money.
Cost+ uses the same API base URL for sandbox and production. The website connected to your API key determines the mode.
3. Copy your API credentials
Open your sandbox website and select Integration. Copy the API key and Merchant ID into your server-side configuration.
Never expose an API key in browser code, a mobile application, screenshots, support messages, or a public repository.
4. Choose an integration path
| Your setup | Recommended path |
|---|---|
| Shopify, WooCommerce, Magento, or another supported platform | Start with the plugin and integration guides. |
| Custom website that should redirect customers to a secure payment form | Use the Hosted Payment Page. |
| Fully custom server-side integration | Follow the Cost+ API quickstart. |
5. Make a sandbox payment
Use the API base URL https://api.costplus.online/v1 with the sandbox website's API key.
For a successful test card payment, use:
- Card number:
4111 1111 1111 1111 - Expiry: any future date
- CVC: any three digits
Test card numbers work only with sandbox credentials. See Testing your integration for declined-payment cards and common validation errors.
6. Confirm the payment result
Confirm that the order appears in the Merchant Portal and reaches the expected status. For a custom integration, verify the result through the Cost+ API or a webhook before fulfilling the order.
Do not treat the customer's browser redirect as proof of payment.
7. Prepare to go live
Before accepting real payments:
- Complete the required onboarding and underwriting for a production website.
- Confirm that the payment methods you need are enabled.
- Replace the sandbox API key with the production website's key in your secure server-side configuration.
- Confirm your return, failure, and webhook URLs use HTTPS and point to the production environment.
- Make a controlled live payment and verify its final status before opening checkout to customers.
Need help?
Read the Cost+ developer documentation or contact Cost+ Support.