Back in Stock: Notifications on Product Arrival

Note: when a product runs out of stock, 80% of buyers go to competitors and never come back. The 'Notify on Arrival' subscription form turns this loss into a lead: you get the contact of an interested person and can bring them back exactly when the product is in stock again. We implement Back in Stock turnkey in 1-2 business days, with integration into your CRM and any communication channels (email, Telegram, SMS). Our engineers have 5+ years of experience in e-commerce; we guarantee stable notification operation even under peak loads. Development cost typically starts at $500 for a basic integration and can go up to $1,500 for multi-channel setup with CRM integration. Businesses report recovering up to 30% of lost sales, translating to thousands of dollars in additional revenue. Contact us for a project assessment and get a free consultation.

How does the notification system work?

The system consists of several modules: a frontend form, an API for subscription, a job queue for sending notifications, and a duplicate protection mechanism. Let's examine each on the example of the Laravel + React stack, but implementation is possible on any platform.

Data schema

CREATE TABLE back_in_stock_requests ( id BIGSERIAL PRIMARY KEY, product_id BIGINT NOT NULL REFERENCES products(id) ON DELETE CASCADE, variant_id BIGINT REFERENCES product_variants(id) ON DELETE CASCADE, user_id BIGINT REFERENCES users(id) ON DELETE SET NULL, email VARCHAR(255) NOT NULL, notified_at TIMESTAMP, created_at TIMESTAMP DEFAULT NOW() ); CREATE UNIQUE INDEX idx_bis_email_product ON back_in_stock_requests(email, product_id, COALESCE(variant_id, 0)) WHERE notified_at IS NULL; 

A unique index prevents duplicate subscriptions from the same email for the same product/variant until the notification is sent.

Subscription form

The form is displayed instead of the 'Add to cart' button when stock = 0:

const BackInStockForm = ({ product, variant }: BackInStockProps) => { const { user } = useAuth(); const [submitted, setSubmitted] = useState(false); const { register, handleSubmit, formState: { errors, isSubmitting } } = useForm({ defaultValues: { email: user?.email ?? '' }, }); const onSubmit = async (data: { email: string }) => { await api.post('/back-in-stock', { product_id: product.id, variant_id: variant?.id ?? null, email: data.email, }); setSubmitted(true); }; if (submitted) { return ( <div className="flex items-center gap-2 text-green-600 text-sm"> <CheckIcon className="w-4 h-4" /> <span>We will notify you when the product is back in stock</span> </div> ); } return ( <form onSubmit={handleSubmit(onSubmit)} className="space-y-2"> <p className="text-sm text-gray-600">This product is out of stock. Leave your email — we'll notify you when it's back.</p> <div className="flex gap-2"> <input type="email" placeholder="[email protected]" className="flex-1 border rounded px-3 py-2 text-sm" {...register('email', { required: true, pattern: /^[^\s@]+@[^\s@]+\.[^\s@]+$/ })} /> <Button type="submit" size="sm" loading={isSubmitting}> Notify me </Button> </div> {errors.email && <p className="text-red-500 text-xs">Please enter a valid email</p>} </form> ); }; 

Subscription API endpoint

public function subscribe(Request $request): JsonResponse { $request->validate([ 'product_id' => 'required|exists:products,id', 'variant_id' => 'nullable|exists:product_variants,id', 'email' => 'required|email|max:255', ]); // Check that the product is really out of stock $product = Product::find($request->product_id); if ($product->stock > 0) { return response()->json(['message' => 'Product is already in stock'], 422); } BackInStockRequest::firstOrCreate([ 'product_id' => $request->product_id, 'variant_id' => $request->variant_id, 'email' => strtolower($request->email), 'notified_at' => null, ], [ 'user_id' => $request->user()?->id, ]); return response()->json(['message' => 'Subscription created']); } 

Why is it important to notify about arrival?

A product with zero stock is not lost demand but deferred demand. Notifications bring back up to 30% of such customers. Form subscription is 2–3 times more effective in conversion than pop-ups, as it does not forcefully interrupt the user. Additionally, subscription analytics helps forecast demand: products with high numbers of waiting people are a signal to reorder from the supplier. Compared to email, Telegram notifications are 2 times more effective in driving purchases, while SMS is 3 times more expensive but yields 2x conversion. On average, 20% of subscribers purchase within 24 hours of notification. The median wait time is 4 days.

How to choose a notification channel?

Email is an economical option for mass notifications, but open rates are lower. Telegram and SMS provide higher conversion, especially for urgent products. We connect any channel of your choice.

Automatic sending when stock is replenished

The trigger fires when stock is updated. This can happen via import from 1С/ERP, manual update in the admin panel, or supplier API. We use a queue (Redis/Beanstalkd) for asynchronous sending to avoid blocking the main thread.

// Observer on Product model — combines check and sending class ProductObserver { public function updated(Product $product): void { if ($product->isDirty('stock') && $product->stock > 0 && $product->getOriginal('stock') === 0) { NotifyBackInStockSubscribers::dispatch($product)->onQueue('notifications'); } } } class NotifyBackInStockSubscribers implements ShouldQueue { public function handle(): void { $requests = BackInStockRequest::where('product_id', $this->product->id) ->whereNull('variant_id') ->whereNull('notified_at') ->get(); foreach ($requests as $request) { Mail::to($request->email)->queue(new BackInStockNotification($this->product, $request)); $request->update(['notified_at' => now()]); } } } 

Features for products with variants

If a product has sizes or colors, the notification must consider the specific variant. In the data schema, the variant_id field allows subscribing to the desired modification. When only the selected variant arrives, only those who waited for it will receive the notification. This increases relevance and conversion.

Email notification

The email contains:

• Product photo and name
• Current price with discounts
• Direct link to the product with UTM tag utm_source=back_in_stock
• Warning: 'Limited quantity – hurry to buy'

The email is sent once – notified_at records the sending time. There are no repeated notifications.

Unsubscription

The 'Unsubscribe' link in the email goes to /back-in-stock/unsubscribe?token={token}. The token is an HMAC signature of the email and product_id, preventing forgery. After clicking, the subscription is removed without requiring login.

Analytics

Products with a high number of subscriptions are a priority for reorder from the supplier. For example, if 50 people subscribed to a product and only 10 units arrived, it's worth increasing the purchase.

What if the notification didn't work?

A rare but possible situation: the product arrived but the notification was not sent. Usually the cause is a job queue failure or incorrect stock state. We set up monitoring (alerts in Telegram/Slack) and automatic retry. In the basic implementation, the queue uses Laravel's retry mechanisms: if an email is not sent, it is retried after 60 seconds, up to 3 attempts.

Deliverables

Turnkey Back in Stock development includes:

• Integration of the subscription form into the product card
• API for saving subscriptions with validation
• Notification queue (email, optionally Telegram/SMS)
• Email templates with responsive design
• Unsubscription mechanism and analytics dashboard
• Documentation (API docs, form integration guide)
• Code (Git repository access)
• Training for your team (1-hour session)
• Support: 30 days post-deployment, 8/5 response within 4 hours

For additional information about the Back in Stock mechanism, you can read on Wikipedia.

Step-by-Step Implementation Guide

1. Form Integration: Add the React component to product pages where stock=0. Ensure the component conditionally renders based on stock count.
2. API Setup: Create the subscription endpoint with validation and stock check. Set up rate limiting to prevent abuse.
3. Queue Configuration: Set up Redis with 5 workers for high load. Install a queue driver like Redis or Beanstalkd.
4. Email Template: Design the notification email with dynamic product info and UTM tags. Use a transactional email service like SendGrid.
5. Unsubscribe Link: Implement token-based unsubscription using HMAC. The link should be part of the email footer.
6. Testing: Send test subscriptions and verify email delivery. Check for spam classification and adjust DKIM/SPF records.
7. Go Live: Deploy to production and monitor for 24 hours. Set up logging for queue failures and alerting.