curl --request POST \
  --url https://api.kas.fyi/v1/rpc/getMempoolEntry \
  --header 'Content-Type: application/json' \
  --header 'x-api-key: <api-key>' \
  --data '
{
  "transactionId": "fc4c90a646687ba6f862e6089285dd7a610ef4d7f7614d25295f65aceb02bc41",
  "includeOrphanPool": false,
  "filterTransactionPool": false
}
'

import requests

url = "https://api.kas.fyi/v1/rpc/getMempoolEntry"

payload = {
    "transactionId": "fc4c90a646687ba6f862e6089285dd7a610ef4d7f7614d25295f65aceb02bc41",
    "includeOrphanPool": False,
    "filterTransactionPool": False
}
headers = {
    "x-api-key": "<api-key>",
    "Content-Type": "application/json"
}

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

print(response.text)

const options = {
  method: 'POST',
  headers: {'x-api-key': '<api-key>', 'Content-Type': 'application/json'},
  body: JSON.stringify({
    transactionId: 'fc4c90a646687ba6f862e6089285dd7a610ef4d7f7614d25295f65aceb02bc41',
    includeOrphanPool: false,
    filterTransactionPool: false
  })
};

fetch('https://api.kas.fyi/v1/rpc/getMempoolEntry', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

<?php

$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => "https://api.kas.fyi/v1/rpc/getMempoolEntry",
  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' => 'fc4c90a646687ba6f862e6089285dd7a610ef4d7f7614d25295f65aceb02bc41',
    'includeOrphanPool' => false,
    'filterTransactionPool' => false
  ]),
  CURLOPT_HTTPHEADER => [
    "Content-Type: application/json",
    "x-api-key: <api-key>"
  ],
]);

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

curl_close($curl);

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

package main

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

func main() {

	url := "https://api.kas.fyi/v1/rpc/getMempoolEntry"

	payload := strings.NewReader("{\n  \"transactionId\": \"fc4c90a646687ba6f862e6089285dd7a610ef4d7f7614d25295f65aceb02bc41\",\n  \"includeOrphanPool\": false,\n  \"filterTransactionPool\": false\n}")

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

	req.Header.Add("x-api-key", "<api-key>")
	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.kas.fyi/v1/rpc/getMempoolEntry")
  .header("x-api-key", "<api-key>")
  .header("Content-Type", "application/json")
  .body("{\n  \"transactionId\": \"fc4c90a646687ba6f862e6089285dd7a610ef4d7f7614d25295f65aceb02bc41\",\n  \"includeOrphanPool\": false,\n  \"filterTransactionPool\": false\n}")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://api.kas.fyi/v1/rpc/getMempoolEntry")

http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true

request = Net::HTTP::Post.new(url)
request["x-api-key"] = '<api-key>'
request["Content-Type"] = 'application/json'
request.body = "{\n  \"transactionId\": \"fc4c90a646687ba6f862e6089285dd7a610ef4d7f7614d25295f65aceb02bc41\",\n  \"includeOrphanPool\": false,\n  \"filterTransactionPool\": false\n}"

response = http.request(request)
puts response.read_body

{
  "mempoolEntry": {
    "fee": "1000",
    "transaction": {
      "version": 1,
      "inputs": [
        {
          "previousOutpoint": {
            "transactionId": "34e9538fd3225652553930657c3d767d5ccab0fcd545038a69c202e45929dcd6",
            "index": 0
          },
          "sequence": "4294967295",
          "sigOpCount": 1,
          "signatureScript": "0x473044..."
        }
      ],
      "outputs": [
        {
          "value": "1000000000",
          "scriptPublicKey": "<string>",
          "verboseData": {
            "scriptPublicKeyType": "pubkeyhash",
            "scriptPublicKeyAddress": "kaspa:qpzpfwcsqsxhxwup26r55fd0ghqlhyugz8cp6y3wxuddc02vcxtjg75pspnwz"
          }
        }
      ],
      "lockTime": "0",
      "subnetworkId": "0100000000000000000000000000000000000000",
      "gas": "0",
      "payload": "0x",
      "mass": "1000",
      "verboseData": {
        "transactionId": "34e9538fd3225652553930657c3d767d5ccab0fcd545038a69c202e45929dcd6",
        "hash": "34e9538fd3225652553930657c3d767d5ccab0fcd545038a69c202e45929dcd6",
        "computeMass": "1000",
        "blockHash": "34e9538fd3225652553930657c3d767d5ccab0fcd545038a69c202e45929dcd6",
        "blockTime": "1638360000000"
      }
    },
    "isOrphan": false
  }
}