Response to json Payload in POST API not in Json Format - php

Question

I have a Rest API that accepts a Json Payload, i format the Data and import this into the SQL Database. However when the payload is received the sender is waiting for a response.
They do not want a Typical HTTP 200 OK, they want a formatted Json Response with the Price etc for the submission.
Whenever i output the response to the body, it does not appear to be formatted as a Json and appears as a string, this is causing errors with the flow of the program.
i wanted to check the formatting is correct and the method.
ignoring all the handler and authorization i am typically picking up the payload via:
$payload = (file_get_contents('php://input'));
do what i need to do with the data
then respond as follow:
(of course this is wrapped in a statement of handlers but the successful segment of the code)
http_response_code(200);
$data = array(
"sub_total" => 1000,
"ExtraeChargeTotal" => 0,
"Vat" => 0,
"Total" => 1000
);
$response = json_encode($data);
echo $response ;
is this the correct way to respond? everything works how i think it should, an appears to work in postman.
however the response is a string and not in Json

Answer 1

To resume the comments, when json datas must been sent with PHP, it's important to force the Content-Type header by this way :
header('Content-Type: application/json; charset=utf-8');
After the header, send the datas with echo.
For exemple in this case :
http_response_code(200);
$data = array(
"sub_total" => 1000,
"ExtraeChargeTotal" => 0,
"Vat" => 0,
"Total" => 1000
);
if($response = json_encode($data)){
header('Content-Type: application/json; charset=utf-8');
echo $response ;
}