$curl = curl_init();
curl_setopt_array($curl, [
	CURLOPT_URL => "https://www.falconebiz.com/api/gst_filing",
	CURLOPT_RETURNTRANSFER => true,
	CURLOPT_TIMEOUT => 30,
	CURLOPT_CUSTOMREQUEST => "GET",
	CURLOPT_HTTPHEADER => [
		"Content-Type: application/json",
		"Authorization: YOUR-API-KEY",
		"Gstin: GST_NUMBER",
		"Fy: 2017-18",
		"Domain: YOUR DOMAIN"
	],
]);

$response = curl_exec($curl);
$err = curl_error($curl);
curl_close($curl);
if($err) {
	echo "cURL Error #:" . $err;
}else{
	echo $response;
}

{
	"data": {
		"EFiledlist": [
			{
				"valid": "Y",
				"mof": "ONLINE",
				"dof": "20-02-2023",
				"rtntype": "GSTR3B",
				"ret_prd": "012023",
				"arn": "AA200123225714W",
				"status":
				"Filed"
			},
			{
				"valid": "Y",
				"mof": "ONLINE",
				"dof": "10-02-2023",
				"rtntype": "GSTR1",
				"ret_prd": "012023",
				"arn": "AA2001230829597",
				"status":
				"Filed"
			}
		]
	}
}