Initialize S2S Card Payment With Wallet

Initialize an S2S card payment that settles into a selected NGN wallet.

This endpoint follows the existing S2S card payment payload and adds wallet_code.

Endpoint

POST /api/s2s/v1/transaction/initialize/wallet

Request Body

curl --request POST \
  --url https://backendapi.sayswitchgroup.com/api/s2s/v1/transaction/initialize/wallet \
  --header "Authorization: Bearer YOUR_SECRET_KEY" \
  --header "Content-Type: application/json" \
  --data '{
    "amount": "10.00",
    "card": "ENCRYPTED_CARD_HEX_STRING",
    "currency": "NGN",
    "email": "test@example.com",
    "pin": "1234",
    "reference": "WALLET_CARD_2026_0001",
    "wallet_code": "NGN169XXXX"
  }'

// Run secret-key requests on your server.
const response = await fetch("https://backendapi.sayswitchgroup.com/api/s2s/v1/transaction/initialize/wallet", {
  method: "POST",
  headers: {
    "Authorization": "Bearer YOUR_SECRET_KEY",
    "Content-Type": "application/json"
  },
  body: JSON.stringify({
    "amount": "10.00",
    "card": "ENCRYPTED_CARD_HEX_STRING",
    "currency": "NGN",
    "email": "test@example.com",
    "pin": "1234",
    "reference": "WALLET_CARD_2026_0001",
    "wallet_code": "NGN169XXXX"
  })
});
 
const responseBody = await response.text();
console.log(response.status, responseBody);

<?php
$request = curl_init('https://backendapi.sayswitchgroup.com/api/s2s/v1/transaction/initialize/wallet');
 
curl_setopt_array($request, [
    CURLOPT_CUSTOMREQUEST => 'POST',
    CURLOPT_RETURNTRANSFER => true,
    CURLOPT_HTTPHEADER => [
        'Authorization: Bearer YOUR_SECRET_KEY',
        'Content-Type: application/json',
    ],
    CURLOPT_POSTFIELDS => '{
    "amount": "10.00",
    "card": "ENCRYPTED_CARD_HEX_STRING",
    "currency": "NGN",
    "email": "test@example.com",
    "pin": "1234",
    "reference": "WALLET_CARD_2026_0001",
    "wallet_code": "NGN169XXXX"
  }',
]);
 
$responseBody = curl_exec($request);
$status = curl_getinfo($request, CURLINFO_HTTP_CODE);
curl_close($request);
 
echo $status . PHP_EOL;
echo $responseBody;

from urllib.request import Request, urlopen
 
payload = "{\n    \"amount\": \"10.00\",\n    \"card\": \"ENCRYPTED_CARD_HEX_STRING\",\n    \"currency\": \"NGN\",\n    \"email\": \"test@example.com\",\n    \"pin\": \"1234\",\n    \"reference\": \"WALLET_CARD_2026_0001\",\n    \"wallet_code\": \"NGN169XXXX\"\n  }".encode()
 
request = Request(
    "https://backendapi.sayswitchgroup.com/api/s2s/v1/transaction/initialize/wallet",
    data=payload,
    method="POST",
    headers={
        "Authorization": "Bearer YOUR_SECRET_KEY",
        "Content-Type": "application/json",
    },
)
 
with urlopen(request) as response:
    response_body = response.read().decode()
    print(response.status, response_body)

import java.net.URI;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;
 
var body = """
    {
        "amount": "10.00",
        "card": "ENCRYPTED_CARD_HEX_STRING",
        "currency": "NGN",
        "email": "test@example.com",
        "pin": "1234",
        "reference": "WALLET_CARD_2026_0001",
        "wallet_code": "NGN169XXXX"
      }
    """;
 
var request = HttpRequest.newBuilder()
    .uri(URI.create("https://backendapi.sayswitchgroup.com/api/s2s/v1/transaction/initialize/wallet"))
    .header("Authorization", "Bearer YOUR_SECRET_KEY")
    .header("Content-Type", "application/json")
    .method("POST", HttpRequest.BodyPublishers.ofString(body))
    .build();
 
var response = HttpClient.newHttpClient().send(
    request,
    HttpResponse.BodyHandlers.ofString()
);
 
System.out.println(response.statusCode());
System.out.println(response.body());

Required Fields

Field	Description
`email`	Customer email address
`amount`	Payment amount
`reference`	Unique transaction reference
`card`	Encrypted card payload generated with the S2S card encryption helper
`wallet_code`	Target NGN wallet code

Optional Fields

Field	Description
`currency`	Defaults to `NGN`
`pin`	May be required depending on the card flow

Card Encryption Helper

The card field must be the encrypted card payload generated using the S2S card encryption helper. Do not use a plain card object or mock string as the card value.

POST /api/s2s/v1/test/encryption

Request Body

curl --request POST \
  --url https://backendapi.sayswitchgroup.com/api/s2s/v1/test/encryption \
  --header "Authorization: Bearer YOUR_SECRET_KEY" \
  --header "Content-Type: application/json" \
  --data '{
    "reference": "WALLET_CARD_2026_0001",
    "data": {
      "number": "4005555555000009",
      "expiryMonth": "05",
      "expiryYear": "37",
      "cvv": "000"
    }
  }'

// Run secret-key requests on your server.
const response = await fetch("https://backendapi.sayswitchgroup.com/api/s2s/v1/test/encryption", {
  method: "POST",
  headers: {
    "Authorization": "Bearer YOUR_SECRET_KEY",
    "Content-Type": "application/json"
  },
  body: JSON.stringify({
    "reference": "WALLET_CARD_2026_0001",
    "data": {
      "number": "4005555555000009",
      "expiryMonth": "05",
      "expiryYear": "37",
      "cvv": "000"
    }
  })
});
 
const responseBody = await response.text();
console.log(response.status, responseBody);

<?php
$request = curl_init('https://backendapi.sayswitchgroup.com/api/s2s/v1/test/encryption');
 
curl_setopt_array($request, [
    CURLOPT_CUSTOMREQUEST => 'POST',
    CURLOPT_RETURNTRANSFER => true,
    CURLOPT_HTTPHEADER => [
        'Authorization: Bearer YOUR_SECRET_KEY',
        'Content-Type: application/json',
    ],
    CURLOPT_POSTFIELDS => '{
    "reference": "WALLET_CARD_2026_0001",
    "data": {
      "number": "4005555555000009",
      "expiryMonth": "05",
      "expiryYear": "37",
      "cvv": "000"
    }
  }',
]);
 
$responseBody = curl_exec($request);
$status = curl_getinfo($request, CURLINFO_HTTP_CODE);
curl_close($request);
 
echo $status . PHP_EOL;
echo $responseBody;

from urllib.request import Request, urlopen
 
payload = "{\n    \"reference\": \"WALLET_CARD_2026_0001\",\n    \"data\": {\n      \"number\": \"4005555555000009\",\n      \"expiryMonth\": \"05\",\n      \"expiryYear\": \"37\",\n      \"cvv\": \"000\"\n    }\n  }".encode()
 
request = Request(
    "https://backendapi.sayswitchgroup.com/api/s2s/v1/test/encryption",
    data=payload,
    method="POST",
    headers={
        "Authorization": "Bearer YOUR_SECRET_KEY",
        "Content-Type": "application/json",
    },
)
 
with urlopen(request) as response:
    response_body = response.read().decode()
    print(response.status, response_body)

import java.net.URI;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;
 
var body = """
    {
        "reference": "WALLET_CARD_2026_0001",
        "data": {
          "number": "4005555555000009",
          "expiryMonth": "05",
          "expiryYear": "37",
          "cvv": "000"
        }
      }
    """;
 
var request = HttpRequest.newBuilder()
    .uri(URI.create("https://backendapi.sayswitchgroup.com/api/s2s/v1/test/encryption"))
    .header("Authorization", "Bearer YOUR_SECRET_KEY")
    .header("Content-Type", "application/json")
    .method("POST", HttpRequest.BodyPublishers.ofString(body))
    .build();
 
var response = HttpClient.newHttpClient().send(
    request,
    HttpResponse.BodyHandlers.ofString()
);
 
System.out.println(response.statusCode());
System.out.println(response.body());

The same reference used for encryption must be used for transaction initialization because the reference is used to derive the encryption IV.

The encryption endpoint returns the hexadecimal card payload directly as a raw text response, not as JSON.

Create NGN Wallet OPay Payment With Wallet