How to get live gold prices in PHP

php -m | grep -E '^(curl|json|bcmath)$'
# curl
# json
# bcmath   <- if missing, install php8.3-bcmath (or enable in php.ini)

<?php
// php: goldprice.php — native cURL + BCMath, no Composer
// curl-equivalent: https://api.goldprice.dev/v1/spot/XAU-USD-SPOT
declare(strict_types=1);

const API_BASE = 'https://api.goldprice.dev';
const TIMEOUT  = 5;   // seconds
const TTL      = 60;  // seconds

final class RateLimitedException extends RuntimeException {}

final class GoldpriceClient
{
    private string $apiKey;

    /** @var array<string, array{data: array, expires: int}> */
    private static array $cache = [];

    public function __construct()
    {
        $key = getenv('GOLDPRICE_API_KEY');
        if ($key === false || $key === '') {
            throw new RuntimeException('GOLDPRICE_API_KEY not set');
        }
        $this->apiKey = $key;
    }

    /**
     * Fetch live spot price. Cached 60s per symbol, retries 3x on 429.
     * Prices stay as strings for BCMath.
     */
    public function spot(string $symbol = 'XAU-USD-SPOT'): array
    {
        $now = time();
        if (isset(self::$cache[$symbol]) && self::$cache[$symbol]['expires'] > $now) {
            return self::$cache[$symbol]['data'];
        }

        for ($attempt = 0; $attempt < 3; $attempt++) {
            try {
                $data = $this->fetch($symbol);
                self::$cache[$symbol] = ['data' => $data, 'expires' => $now + TTL];
                return $data;
            } catch (RateLimitedException) {
                sleep(1 << $attempt); // 1s, 2s, 4s
            }
        }
        throw new RateLimitedException('goldprice: 429 after 3 retries');
    }

    private function fetch(string $symbol): array
    {
        $ch = curl_init(API_BASE . '/v1/spot/' . rawurlencode($symbol));
        curl_setopt_array($ch, [
            CURLOPT_RETURNTRANSFER => true,
            CURLOPT_TIMEOUT        => TIMEOUT,
            CURLOPT_HTTPHEADER     => ['X-API-Key: ' . $this->apiKey],
        ]);
        $body = curl_exec($ch);
        $code = curl_getinfo($ch, CURLINFO_RESPONSE_CODE);
        curl_close($ch);

        if ($code === 429) {
            throw new RateLimitedException('rate limited');
        }
        if ($code !== 200 || $body === false) {
            throw new RuntimeException("goldprice: unexpected status {$code}");
        }

        return json_decode((string) $body, true, 512, JSON_THROW_ON_ERROR);
    }
}

$client = new GoldpriceClient();
$r = $client->spot('XAU-USD-SPOT');

// Prices are strings; use BCMath for exact math (e.g. price for 5 oz):
$fiveOz = bcmul($r['price'], '5', 4);

printf("%s-%s: %s (computed %s)\n", $r['symbol'], $r['quote_currency'], $r['price'], $r['computed_at']);
printf("5 troy oz = %s %s\n", $fiveOz, $r['quote_currency']);

php goldprice.php
# XAU-USD: 4726.01 (computed 2026-06-26T04:49:01.706844+00:00)
# 5 troy oz = 23630.0500 USD

$client = new GoldpriceClient();

// USD spot — default
$client->spot('XAU-USD-SPOT');

// INR — Indian gold market (largest retail gold-search globally)
$client->spot('XAU-INR-SPOT');

// EUR — European pricing surfaces
$client->spot('XAU-EUR-SPOT');

// Silver in USD
$client->spot('XAG-USD-SPOT');