WhatsApp API PHP Integration: Send Messages with PHP in 2026

<?php

define('WALYTIC_API_KEY', getenv('WALYTIC_API_KEY'));
define('WALYTIC_INSTANCE_ID', getenv('WALYTIC_INSTANCE_ID'));
define('WALYTIC_BASE_URL', 'https://api.walytic.com/api');

function walytic_post(string $endpoint, array $payload): array {
    $ch = curl_init(WALYTIC_BASE_URL . $endpoint);

    curl_setopt_array($ch, [
        CURLOPT_RETURNTRANSFER => true,
        CURLOPT_POST           => true,
        CURLOPT_POSTFIELDS     => json_encode($payload),
        CURLOPT_HTTPHEADER     => [
            'Authorization: Bearer ' . WALYTIC_API_KEY,
            'Content-Type: application/json',
        ],
        CURLOPT_TIMEOUT        => 10,
    ]);

    $response = curl_exec($ch);
    $status   = curl_getinfo($ch, CURLINFO_HTTP_CODE);
    curl_close($ch);

    if ($response === false || $status >= 400) {
        return ['success' => false, 'error' => "HTTP $status"];
    }

    return json_decode($response, true) ?? ['success' => false];
}

WALYTIC_API_KEY=your_api_key_here
WALYTIC_INSTANCE_ID=your_instance_id_here

function send_text(string $phone, string $message): bool {
    $result = walytic_post('/messages/send', [
        'instanceId' => WALYTIC_INSTANCE_ID,
        'to'         => $phone,
        'type'       => 'text',
        'text'       => ['body' => $message],
    ]);

    return $result['success'] ?? false;
}

// Usage
send_text('14155552671', 'Hi Sarah! Your order #1042 has shipped and arrives Friday.');

// Send an image with a caption
function send_image(string $phone, string $url, string $caption = ''): bool {
    $result = walytic_post('/messages/send', [
        'instanceId' => WALYTIC_INSTANCE_ID,
        'to'         => $phone,
        'type'       => 'image',
        'image'      => ['url' => $url, 'caption' => $caption],
    ]);

    return $result['success'] ?? false;
}

// Send a PDF document
function send_document(string $phone, string $url, string $filename): bool {
    $result = walytic_post('/messages/send', [
        'instanceId' => WALYTIC_INSTANCE_ID,
        'to'         => $phone,
        'type'       => 'document',
        'document'   => ['url' => $url, 'filename' => $filename],
    ]);

    return $result['success'] ?? false;
}

// Examples
send_image('14155552671', 'https://yoursite.com/product.jpg', 'Your order is packed!');
send_document('14155552671', 'https://yoursite.com/invoice-1042.pdf', 'Invoice-1042.pdf');

<?php
// webhook.php — your public HTTPS endpoint

$payload = json_decode(file_get_contents('php://input'), true);

if (($payload['event'] ?? '') === 'message.received') {
    $from = $payload['data']['from'];
    $text = strtolower(trim($payload['data']['text']['body'] ?? ''));

    if ($text === 'order status') {
        walytic_post('/messages/send', [
            'instanceId' => WALYTIC_INSTANCE_ID,
            'to'         => $from,
            'type'       => 'text',
            'text'       => ['body' => 'Please reply with your order number and we will look it up.'],
        ]);
    } elseif ($text === 'hours') {
        walytic_post('/messages/send', [
            'instanceId' => WALYTIC_INSTANCE_ID,
            'to'         => $from,
            'type'       => 'text',
            'text'       => ['body' => 'We are open Mon-Fri 9 am-6 pm. How can we help?'],
        ]);
    }
}

http_response_code(200);
echo 'ok';

function notify_order_shipped(array $order): void {
    $message = "Hi {$order['customer_name']}! Order #{$order['id']} has shipped. "
             . "Track it here: {$order['tracking_url']}";

    send_text($order['phone'], $message);
}

function send_appointment_reminder(array $booking): void {
    $message = "Reminder: your appointment with {$booking['provider']} "
             . "is tomorrow at {$booking['time']}. "
             . "Reply YES to confirm or CANCEL to reschedule.";

    send_text($booking['phone'], $message);
}

function send_payment_reminder(array $invoice): void {
    $amount  = number_format($invoice['amount'], 2);
    $message = "Hi {$invoice['client_name']}, invoice #{$invoice['id']} "
             . "for $$amount is overdue. Pay here: {$invoice['payment_link']}";

    send_text($invoice['phone'], $message);
}

function send_text_with_retry(string $phone, string $message, int $max_retries = 3): bool {
    for ($i = 0; $i < $max_retries; $i++) {
        if (send_text($phone, $message)) {
            return true;
        }
        sleep(1 << $i); // 1s, 2s, 4s
    }
    error_log("WhatsApp delivery failed after $max_retries attempts to $phone");
    return false;
}