JSON Encode Online

json_encode() turns a PHP value, usually an array, into a JSON string you can send from an API, save to a file or pass to JavaScript. It is the opposite of json_decode(). This is how each PHP type is written:

1. Paste your PHP array as you’d write it in code, with [ ] or array( ). A leading $data =, a trailing semicolon and comments are fine. You can paste JSON too.
2. Turn on flags such as JSON_PRETTY_PRINT. The line above the result shows the exact call to copy into your code.
3. Copy the JSON. If PHP would fail, you see false and the message json_last_error_msg() would return.

Variables and function calls can’t run here, so paste their values instead.

Combine flags with |, for example JSON_PRETTY_PRINT | JSON_UNESCAPED_SLASHES. The ones people use most:

Be careful with JSON_NUMERIC_CHECK: it also changes phone numbers and ZIP codes, so "01234" becomes 1234. Cast the fields you mean with (int) instead.

• An array turns into an object. JSON lists can only have keys 0, 1, 2… in order. After unset() or array_filter() there are gaps, so PHP writes {"0":"red","2":"blue"}. Use array_values($colors) to renumber it. Load Array with gaps above to see it.
• It returns false. Usually a string isn’t valid UTF-8 (text from an old database or a Windows-1252 file), giving Malformed UTF-8 characters. Convert it with mb_convert_encoding($s, 'UTF-8', 'Windows-1252'), or pass JSON_INVALID_UTF8_SUBSTITUTE. INF and NAN also fail: JSON has no value for them.
• Object properties are missing. Only public properties are encoded. Implement JsonSerializable to choose what goes out.
• The output has \" everywhere. You encoded a string that was already JSON. Encode the array once, not its JSON.

To return JSON from a PHP script or API:

header('Content-Type: application/json; charset=utf-8');
echo json_encode($data, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE | JSON_THROW_ON_ERROR);
exit;

MATLAB’s jsonencode works like PHP’s: a struct becomes a JSON object and an array becomes a JSON array. Other languages have their own function:

% MATLAB (PrettyPrint needs R2021a or later)
s.name = "Zoë"; s.tags = ["php", "json"];
txt = jsonencode(s)                        % {"name":"Zoë","tags":["php","json"]}
txt = jsonencode(s, PrettyPrint=true)

# Python
json.dumps(data, ensure_ascii=False, indent=4)

// JavaScript
JSON.stringify(data, null, 4)

// C#
JsonSerializer.Serialize(data)

For a closer look at indentation, naming and null settings in C#, Java and Python, see JSON Serialize Online.