How to convert PHP array to JSON?

Use json_encode($array). Example: json_encode(['name' => 'John']) returns '{"name":"John"}'.

How to pretty print JSON in PHP?

Use JSON_PRETTY_PRINT flag: json_encode($data, JSON_PRETTY_PRINT) adds indentation and line breaks.

What does json_encode return on failure?

json_encode() returns false on failure. Use json_last_error() and json_last_error_msg() to get error details.

PHP json_encode() Function

JSON Function PHP 5.2.0+

The json_encode() function converts a PHP value (array, object, etc.) to a JSON-formatted string.

Syntax

json_encode(mixed $value, int $flags = 0, int $depth = 512): string|false

Parameters

Parameter	Type	Description
`$value`	mixed	The value to encode (array, object, string, number, etc.)
`$flags`	int	Bitmask of JSON constants (optional)
`$depth`	int	Maximum nesting depth (default: 512)

Return Value

Returns a JSON encoded string on success, or false on failure.

Try It Online

<?php
// json_encode() - Convert PHP value to JSON
// Essential for APIs and data exchange

// Example 1: Simple array
$fruits = ["apple", "banana", "cherry"];
echo "Array to JSON:\n";
echo json_encode($fruits) . "\n\n";

// Example 2: Associative array (becomes JSON object)
$user = [
    "name" => "John Doe",
    "email" => "john@example.com",
    "age" => 30,
    "active" => true
];
echo "Object to JSON:\n";
echo json_encode($user) . "\n\n";

// Example 3: Pretty print
echo "Pretty printed:\n";
echo json_encode($user, JSON_PRETTY_PRINT) . "\n\n";

// Example 4: Nested data structure
$response = [
    "success" => true,
    "data" => [
        "users" => [
            ["id" => 1, "name" => "Alice"],
            ["id" => 2, "name" => "Bob"]
        ],
        "total" => 2
    ],
    "message" => "Users retrieved successfully"
];

echo "API Response:\n";
echo json_encode($response, JSON_PRETTY_PRINT) . "\n\n";

// Example 5: Using flags
$data = [
    "url" => "https://example.com/api/users",
    "greeting" => "Hello World!"
];

echo "With UNESCAPED_SLASHES:\n";
echo json_encode($data, JSON_UNESCAPED_SLASHES | JSON_PRETTY_PRINT) . "\n";

Output

Click Run to execute your code

Common Flags

Flag	Description
`JSON_PRETTY_PRINT`	Format output with whitespace for readability
`JSON_UNESCAPED_UNICODE`	Don't escape Unicode characters
`JSON_UNESCAPED_SLASHES`	Don't escape forward slashes
`JSON_FORCE_OBJECT`	Output object instead of array
`JSON_NUMERIC_CHECK`	Encode numeric strings as numbers

More Examples

Pretty Print

<?php
$data = [
    "name" => "John",
    "age" => 30,
    "city" => "NYC"
];

echo json_encode($data, JSON_PRETTY_PRINT);
/*
{
    "name": "John",
    "age": 30,
    "city": "NYC"
}
*/
?>

Combining Flags

<?php
$data = [
    "url" => "https://example.com/api",
    "message" => "Hello World!"
];

$json = json_encode($data,
    JSON_PRETTY_PRINT |
    JSON_UNESCAPED_SLASHES |
    JSON_UNESCAPED_UNICODE
);
echo $json;
?>

API Response

<?php
header('Content-Type: application/json');

$response = [
    "success" => true,
    "data" => [
        "id" => 123,
        "name" => "Product"
    ]
];

echo json_encode($response);
?>

Important: Always check for errors using json_last_error() after encoding, especially with user-provided data.

Common Use Cases

Building REST API responses
Storing data in databases
Passing data to JavaScript
Configuration file generation

Related Functions

json_decode() - Decode a JSON string
json_last_error() - Get last JSON error
json_last_error_msg() - Get error message

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