json_validate()—the lean way to sanity-check JSON in PHP 8.3+

A lightweight guardrail for PHP 8.3-plus that validates JSON without the overhead of decoding.

Photo by Ferenc Almasi on Unsplash

When PHP 8.3 landed on 23 November 2023 it quietly shipped a new standard-library helper: json_validate() .
At first glance the function looks almost trivial—it just returns true or false—but it fills a long-standing gap in the language.

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Why we needed something new

Until 8.3 every production code-base followed one of three patterns:

1. Decode-and-check

$data = json_decode($raw);
if (json_last_error() !== JSON_ERROR_NONE) {
    /* handle error */
}

2. This works, but json_decode() builds PHP arrays/objects even if you throw the result away. That costs memory and CPU for large payloads .

3. Exception mode (PHP 7.3+)

try {
     $data = json_decode($raw, flags: JSON_THROW_ON_ERROR);
} catch (JsonException $e) {
     // handle
}

4. Clearer control flow, but still forces a full decode.