Number plate lookup in PHP

Here is everything you need to look up a number plate from PHP. The example only uses what comes with PHP (cURL), so there is nothing to install.

The lookup

<?php
function lookupPlate(string $country, string $plate): ?array
{
    $key = getenv('PLATERUNNER_KEY');
    $plate = strtoupper(preg_replace('/[\s-]/', '', $plate));
    $url = "https://api.platerunner.dk/v1/plates/{$country}/" . rawurlencode($plate);

    $ch = curl_init($url);
    curl_setopt_array($ch, [
        CURLOPT_RETURNTRANSFER => true,
        CURLOPT_TIMEOUT => 5,
        CURLOPT_HTTPHEADER => ["Authorization: Bearer {$key}"],
    ]);
    $body = curl_exec($ch);
    $status = curl_getinfo($ch, CURLINFO_RESPONSE_CODE);
    curl_close($ch);

    if ($status === 404) {
        return null; // the plate does not exist
    }
    if ($status !== 200 || $body === false) {
        throw new RuntimeException("PlateRunner responded {$status}");
    }
    return json_decode($body, true);
}

$car = lookupPlate('DK', 'AB 12 345');
echo $car ? "{$car['make']} {$car['model']}" : 'Not found';

Put the key in an environment variable (PLATERUNNER_KEY), never directly in the code.

Save the response

A vehicle’s data rarely changes. Save the response in your own database when you have looked up a plate, so the same vehicle does not cost another lookup next time. It saves both time and lookups.

Errors you need to handle

• 404: the plate does not exist. Show a friendly message and let the user enter the vehicle manually.
• 429: this month’s lookups are used, or too many arrived at once. Try again later, or upgrade the plan.
• 401: the key is missing or incorrect.

See getting started for every field in the response.