const options = {
  method: 'POST',
  headers: {Authorization: 'Bearer <token>', 'Content-Type': 'application/json'},
  body: JSON.stringify({transactionId: 'txn_01j7b6f9p5y9h', narration: 'Customer refund'})
};

fetch('https://api.fingopay.io/v1/mpesa/reverse', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

import requests

url = "https://api.fingopay.io/v1/mpesa/reverse"

payload = {
    "transactionId": "txn_01j7b6f9p5y9h",
    "narration": "Customer refund"
}
headers = {
    "Authorization": "Bearer <token>",
    "Content-Type": "application/json"
}

response = requests.post(url, json=payload, headers=headers)

print(response.text)

curl --request POST \
  --url https://api.fingopay.io/v1/mpesa/reverse \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "transactionId": "txn_01j7b6f9p5y9h",
  "narration": "Customer refund"
}
'

package main

import (
	"fmt"
	"strings"
	"net/http"
	"io"
)

func main() {

	url := "https://api.fingopay.io/v1/mpesa/reverse"

	payload := strings.NewReader("{\n  \"transactionId\": \"txn_01j7b6f9p5y9h\",\n  \"narration\": \"Customer refund\"\n}")

	req, _ := http.NewRequest("POST", url, payload)

	req.Header.Add("Authorization", "Bearer <token>")
	req.Header.Add("Content-Type", "application/json")

	res, _ := http.DefaultClient.Do(req)

	defer res.Body.Close()
	body, _ := io.ReadAll(res.Body)

	fmt.Println(string(body))

}

HttpResponse<String> response = Unirest.post("https://api.fingopay.io/v1/mpesa/reverse")
  .header("Authorization", "Bearer <token>")
  .header("Content-Type", "application/json")
  .body("{\n  \"transactionId\": \"txn_01j7b6f9p5y9h\",\n  \"narration\": \"Customer refund\"\n}")
  .asString();

<?php

$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => "https://api.fingopay.io/v1/mpesa/reverse",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "POST",
  CURLOPT_POSTFIELDS => json_encode([
    'transactionId' => 'txn_01j7b6f9p5y9h',
    'narration' => 'Customer refund'
  ]),
  CURLOPT_HTTPHEADER => [
    "Authorization: Bearer <token>",
    "Content-Type: application/json"
  ],
]);

$response = curl_exec($curl);
$err = curl_error($curl);

curl_close($curl);

if ($err) {
  echo "cURL Error #:" . $err;
} else {
  echo $response;
}

using RestSharp;


var options = new RestClientOptions("https://api.fingopay.io/v1/mpesa/reverse");
var client = new RestClient(options);
var request = new RestRequest("");
request.AddHeader("Authorization", "Bearer <token>");
request.AddJsonBody("{\n  \"transactionId\": \"txn_01j7b6f9p5y9h\",\n  \"narration\": \"Customer refund\"\n}", false);
var response = await client.PostAsync(request);

Console.WriteLine("{0}", response.Content);

{
  "status": "success",
  "message": "Reversal initiated successfully",
  "data": {
    "transactionId": "txn_01j7refund"
  }
}

{
  "error": {
    "message": "<string>",
    "param": "<string>",
    "requestId": "<string>"
  }
}

{
  "error": {
    "message": "<string>",
    "param": "<string>",
    "requestId": "<string>"
  }
}

{
  "error": {
    "message": "<string>",
    "param": "<string>",
    "requestId": "<string>"
  }
}

{
  "error": {
    "message": "<string>",
    "param": "<string>",
    "requestId": "<string>"
  }
}

{
  "error": {
    "message": "<string>",
    "param": "<string>",
    "requestId": "<string>"
  }
}

{
  "error": {
    "message": "<string>",
    "param": "<string>",
    "requestId": "<string>"
  }
}