How to Send JSON Response in PHP: Simple Guide

To send a JSON response in PHP, use header('Content-Type: application/json') to set the response type, then output your data with echo json_encode($data). This tells the browser to expect JSON and sends your PHP array or object as a JSON string.

Syntax

To send JSON from PHP, you first set the HTTP header to tell the browser the content is JSON. Then you convert your PHP data to a JSON string and print it.

• header('Content-Type: application/json'): Sets the response type to JSON.
• json_encode($data): Converts PHP arrays or objects to JSON format.
• echo: Sends the JSON string to the client.

php

<?php
header('Content-Type: application/json');
$data = ['key' => 'value'];
echo json_encode($data);
?>

Output

{"key":"value"}

Example

This example shows how to send a JSON response with a list of users. It sets the header, creates an array, converts it to JSON, and sends it.

php

<?php
header('Content-Type: application/json');
$users = [
    ['id' => 1, 'name' => 'Alice'],
    ['id' => 2, 'name' => 'Bob'],
    ['id' => 3, 'name' => 'Charlie']
];
echo json_encode($users);
?>

Output

[{"id":1,"name":"Alice"},{"id":2,"name":"Bob"},{"id":3,"name":"Charlie"}]

Common Pitfalls

Common mistakes when sending JSON in PHP include:

• Not setting the Content-Type header, so the client doesn't know the response is JSON.
• Outputting extra whitespace or HTML before the JSON, which breaks the JSON format.
• Trying to encode resources or unsupported data types, which causes json_encode to fail.

Always call header() before any output and check your data is JSON-serializable.

php

<?php
// Wrong way: header after output
// echo 'Hello';
// header('Content-Type: application/json'); // This will cause an error

// Right way:
header('Content-Type: application/json');
$data = ['success' => true];
echo json_encode($data);
?>

Output

{"success":true}

Quick Reference

Step	Code	Purpose
1	header('Content-Type: application/json');	Set response type to JSON
2	$data = [...];	Prepare PHP data (array or object)
3	echo json_encode($data);	Convert and send JSON string

Key Takeaways

Always set the Content-Type header to application/json before output.

Use json_encode() to convert PHP data to JSON format.

Avoid any output before setting headers to prevent errors.

Ensure your data contains only JSON-serializable types.

Test your JSON output to confirm it is valid and well-formed.