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Introduction
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Introduction - Online Payments

Welcome to the Online Payments module! This guide will walk you through the most important steps needed to start accepting payments using our API. In just a few minutes, you'll generate your first transaction.

1. Prerequisites

Before sending your first API request, you need to prepare two things in the SimPay Client Panel:

  1. Service registration: Go to the Client Panel and add a new service for Online Payments. After creating it, you will receive a unique service identifier (e.g., e65c7519), which will be required when generating each transaction ( you will provide it in the URL).
  2. API Key (Bearer Token): Authentication in our API is done using tokens. You can find your API key after logging into the panel, under the My Account > API Keys tab.
Test mode

To test payments without using real money and actually charging accounts, simply enable "Test mode" in the settings of your specific service in the Client Panel.

2. API Communication Basics

Our API is designed in the REST spirit and communicates exclusively in JSON format.

Every request sent to SimPay servers must absolutely include security in the form of a token and appropriate HTTP headers. Missing the Content-Type header may result in request rejection.

Authorization: Bearer YOUR_API_KEY
Accept: application/json
Content-Type: application/json

3. Generating Your First Transaction

To create a new payment transaction and generate a link for the customer, send a POST request to the endpoint /payment/{serviceId}/transactions, replacing {serviceId} with your service identifier.

Example Request

Below is the simplest possible request. According to the specification, the only absolutely required field in the request body is the amount (amount).

POST /payment/e65c7519/transactions HTTP/1.1
Host: api.simpay.pl
Authorization: Bearer YOUR_API_KEY
Accept: application/json
Content-Type: application/json

{
  "amount": 100.00,
  "currency": "PLN"
}

Want to send more data? You can optionally provide the customer's email address, restrict available payment channels, or force a specific gateway language. The full list and structure of all supported parameters can be found in our API Reference.

Example Response

Upon successful transaction creation, the server will return an HTTP 200 OK status and a JSON object containing the transaction identifier and redirectUrl – the address to which you should redirect the buyer.

{
  "success": true,
  "data": {
    "transactionId": "1d87a1b3-18f8-4146-bcb1-c0c9f293b04f",
    "redirectUrl": "https://pay.simpay.pl/1d87a1b3-18f8-4146-bcb1-c0c9f293b04f"
  }
}

What now? Redirect your customer's browser to the address provided in the redirectUrl field. The customer will pay for the order on our gateway, and we'll take care of the rest!

4. What's Next?

You've successfully generated your first transaction! To build a complete and fully automated e-commerce integration, explore the following topics:

👉 IPN Notifications (Webhooks) – an absolute must! Learn how your server should automatically find out that the customer has actually paid for the order, so you can deliver the goods.

👉 Payments bypassing the gateway (directChannel) – learn how to implement White-Label Checkout and increase conversion in your store.

👉 Transaction status list – learn the full payment lifecycle.

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