curl --request POST \
  --url https://api.kas.fyi/v1/rpc/getBlocks \
  --header 'Content-Type: application/json' \
  --header 'x-api-key: <api-key>' \
  --data '
{
  "includeBlocks": true,
  "includeTransactions": true,
  "lowHash": "fc4c90a646687ba6f862e6089285dd7a610ef4d7f7614d25295f65aceb02bc41"
}
'

import requests

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

payload = {
    "includeBlocks": True,
    "includeTransactions": True,
    "lowHash": "fc4c90a646687ba6f862e6089285dd7a610ef4d7f7614d25295f65aceb02bc41"
}
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({
    includeBlocks: true,
    includeTransactions: true,
    lowHash: 'fc4c90a646687ba6f862e6089285dd7a610ef4d7f7614d25295f65aceb02bc41'
  })
};

fetch('https://api.kas.fyi/v1/rpc/getBlocks', 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/getBlocks",
  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([
    'includeBlocks' => true,
    'includeTransactions' => true,
    'lowHash' => 'fc4c90a646687ba6f862e6089285dd7a610ef4d7f7614d25295f65aceb02bc41'
  ]),
  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/getBlocks"

	payload := strings.NewReader("{\n  \"includeBlocks\": true,\n  \"includeTransactions\": true,\n  \"lowHash\": \"fc4c90a646687ba6f862e6089285dd7a610ef4d7f7614d25295f65aceb02bc41\"\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/getBlocks")
  .header("x-api-key", "<api-key>")
  .header("Content-Type", "application/json")
  .body("{\n  \"includeBlocks\": true,\n  \"includeTransactions\": true,\n  \"lowHash\": \"fc4c90a646687ba6f862e6089285dd7a610ef4d7f7614d25295f65aceb02bc41\"\n}")
  .asString();

require 'uri'
require 'net/http'

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

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  \"includeBlocks\": true,\n  \"includeTransactions\": true,\n  \"lowHash\": \"fc4c90a646687ba6f862e6089285dd7a610ef4d7f7614d25295f65aceb02bc41\"\n}"

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

{
  "blockHashes": [
    "fc4c90a646687ba6f862e6089285dd7a610ef4d7f7614d25295f65aceb02bc41",
    "21e4944392af43783de33dd076c65dd3f5fd57ddaf6fd9f68674d33b54f1b575"
  ],
  "blocks": [
    {
      "header": {
        "hash": "34e9538fd3225652553930657c3d767d5ccab0fcd545038a69c202e45929dcd6",
        "version": 1,
        "parentsByLevel": [
          [
            "0x1234567890abcdef..."
          ],
          [
            "0x9876543210fedcba..."
          ]
        ],
        "hashMerkleRoot": "34e9538fd3225652553930657c3d767d5ccab0fcd545038a69c202e45929dcd6",
        "acceptedIdMerkleRoot": "34e9538fd3225652553930657c3d767d5ccab0fcd545038a69c202e45929dcd6",
        "utxoCommitment": "34e9538fd3225652553930657c3d767d5ccab0fcd545038a69c202e45929dcd6",
        "timestamp": "1638360000000",
        "bits": 393216,
        "nonce": "12345678901234567890",
        "daaScore": "1234567",
        "blueWork": "123456789012345",
        "blueScore": "1234567",
        "pruningPoint": "34e9538fd3225652553930657c3d767d5ccab0fcd545038a69c202e45929dcd6"
      },
      "transactions": [
        {
          "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"
          }
        }
      ],
      "verboseData": {
        "hash": "34e9538fd3225652553930657c3d767d5ccab0fcd545038a69c202e45929dcd6",
        "difficulty": 1.5,
        "selectedParentHash": "34e9538fd3225652553930657c3d767d5ccab0fcd545038a69c202e45929dcd6",
        "transactionIds": [
          "34e9538fd3225652553930657c3d767d5ccab0fcd545038a69c202e45929dcd6",
          "0x9876543210fedcba9876543210fedcba9876543210fedcba9876543210fedcba"
        ],
        "isHeaderOnly": false,
        "blueScore": 1234567,
        "childrenHashes": [
          "34e9538fd3225652553930657c3d767d5ccab0fcd545038a69c202e45929dcd6"
        ],
        "mergeSetBluesHashes": [
          "34e9538fd3225652553930657c3d767d5ccab0fcd545038a69c202e45929dcd6"
        ],
        "mergeSetRedsHashes": [
          "0x9876543210fedcba9876543210fedcba9876543210fedcba9876543210fedcba"
        ],
        "isChainBlock": true
      }
    }
  ]
}