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Merchant API
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Start Checkout

Endpoint signature
This endpoint requires an API key. Read our authentication guide for more information.
POST https://api.reservepay.com/merchants/start-checkout HTTP/1.1
Content-Type: application/json
Accept: application/json
Authorization: Bearer <token>
{
installation_id: string,
amount: string,
currency: string,
return_url: string,
customer_id: string?,
customer_email: string?,
customer_mobile: string?,
customer_name: string?,
}
Returns: object
New to Reservepay? Read our guide on how to call endpoints to get started.
Request arguments
installation_id string

Required. The installation ID for this platform (e.g. your iOS app, Android app, website, or terminal).

amount string

Required. The payment amount in the smallest currency unit (e.g. cents). Must be a positive integer.

currency string

Required. The three-letter ISO currency code (e.g. THB). Must match the funding currency configured for your provider.

return_url string

Required. The URL where we'll redirect your customer after they complete the payment flow. Should be a page that can handle both successful and failed payments.

customer_id string

Optional. Either a Customer ID (starting with cst_) or your own external customer identifier. We'll link this payment to an existing customer if found, or create a new customer if not. This helps track payment history per customer.

If you provide your own external ID and a customer with that ID doesn't exist, we'll create a new customer using that ID as their external identifier.

customer_email string

Optional. Customer's email address. Required if the installation is configured to require email capture.

customer_mobile string

Optional. Customer's mobile phone number. Required if the installation is configured to require mobile capture.

customer_name string

Optional. Customer's name.

Response attributes
Attribute Description
checkout_id
string

Always present. The unique identifier for the checkout
amount
string

Always present. The payment amount in the smallest currency unit (e.g. cents).
currency
string

Always present. The currency code for the payment amount
installation_id
string

Always present. The unique identifier of the merchant installation associated with this checkout
customer_id
string

Nullable. The unique identifier of the customer making the payment
customer_email
string

Nullable. The email address of the customer
customer_mobile
string

Nullable. The mobile phone number of the customer
customer_name
string

Nullable. The name of the customer
redirect_url
string

Always present. The URL where the customer will be redirected to make payment
payment_id
string

Nullable. The unique identifier of the payment associated with this checkout. When nil, the payment has not been paid yet.
Errors common to all endpoints
UNHANDLED_ERROR

This error occurs when the server encounters an unexpected internal error that it cannot handle gracefully. This typically happens due to bugs, infrastructure issues, or edge cases that weren't anticipated during development.

INVALID_ARGUMENTS

This error occurs when the request contains invalid or missing parameters. Common cases include missing required fields, or values that don't match the expected format or type.

BAD_VERSION

This error occurs when making requests to an API version that does not exist. This commonly happens when using an outdated SDK or when the API version specified in the request URL is incorrect.

Open in Markdown
CODE SAMPLES
curl
curl "https://api.reservepay.com/merchants/start-checkout" \
  -X POST
  -H "Content-Type: application/json" \
  -H "Accept: application/json" \
  -H "Authorization: Bearer $(RESERVEPAY_API_KEY)" \
  -d '{
        "installation_id": "ins_xhB46ypq9G",
        "amount": "150050",
        "currency": "THB",
        "return_url": "https://myshop.com/checkout_done"
      }'
Learn how to run these code samples in your terminal by reading our guide.