finsilabs/push-notifications

Push Notifications

Overview

Web push notifications deliver timely messages to subscribers even when they are not on your site — for back-in-stock alerts, price drops, and cart reminders. Push requires explicit browser permission, making the opt-in prompt timing critical. For Shopify, WooCommerce, and BigCommerce, dedicated push notification apps (PushOwl, OneSignal) handle all the subscriber management, triggering logic, and delivery without custom service worker code.

When to Use This Skill

• When adding back-in-stock notifications to replace static "notify me" email forms
• When recovering abandoned carts via a browser push channel alongside email
• When building a price-watch feature for wishlisted items
• When email deliverability is poor and a supplemental channel is needed
• When targeting mobile-first markets where push opt-in rates exceed email opt-in

Core Instructions

Step 1: Choose the right push notification platform

| Platform | Best For | Shopify | WooCommerce | BigCommerce | Price | |----------|---------|---------|-------------|-------------|-------| | PushOwl | Shopify-native, back-in-stock + abandonment | App Store | — | — | Free tier; $19+/mo | | OneSignal | All platforms, free tier, highly configurable | Via JS tag | Plugin | Via JS tag | Free tier; $9+/mo | | Klaviyo Web Push | Already using Klaviyo for email | App Store | Plugin | App Marketplace | Included in Klaviyo | | PushEngage | WooCommerce + segmented campaigns | — | Plugin | Via JS tag | Free tier; $9+/mo |

Shopify recommendation: Use PushOwl — it's the most integrated Shopify push app with built-in back-in-stock, cart abandonment, and shipping alerts.

WooCommerce recommendation: Use PushEngage or OneSignal — both have WordPress plugins and handle subscriber management automatically.

Step 2: Set up push notifications

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Shopify with PushOwl

1. Install PushOwl from the Shopify App Store
2. Go to PushOwl → Settings → Opt-in Prompt and configure:
   • Delay the prompt: set it to trigger after a customer views 2+ pages or adds an item to cart
   • Opt-in message: "Get notified when items are back in stock and for price drops"
3. Go to PushOwl → Automations → Back in Stock and enable it — PushOwl automatically adds a "Notify Me" button to out-of-stock products and fires the push when inventory is replenished
4. Go to PushOwl → Automations → Cart Abandonment and enable it:
   • Set timing: 1 hour after abandonment, then 24 hours
   • Customize the notification message and the cart recovery URL
5. Go to PushOwl → Campaigns to send broadcast push notifications for sales, new arrivals, or flash discounts

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WooCommerce with PushEngage

1. Install PushEngage from the WordPress plugin directory (free tier available)
2. Go to PushEngage → Settings → Subscription Prompt and configure the opt-in dialog
3. Enable automated campaigns:
   • Go to PushEngage → Automation → Cart Abandonment and set the timing and message
   • Go to PushEngage → Automation → Back in Stock and enable it (requires WooCommerce stock event integration)
4. For price drop alerts: go to PushEngage → Automation → Price Drop Alert and enable subscriber opt-in per product
5. Use PushEngage → Broadcast to send manual push campaigns to all subscribers

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BigCommerce with OneSignal

1. Sign up for OneSignal at onesignal.com and create a Web Push app
2. Go to OneSignal → Settings → Web Push → Setup and follow the HTTPS domain verification
3. Add the OneSignal JavaScript snippet to your BigCommerce store via Storefront → Script Manager:

   <script src="https://cdn.onesignal.com/sdks/web/v16/OneSignalSDK.page.js" defer></script>
   <script>
     window.OneSignalDeferred = window.OneSignalDeferred || [];
     OneSignalDeferred.push(async function(OneSignal) {
       await OneSignal.init({ appId: "YOUR_APP_ID" });
     });
   </script>
   

4. For back-in-stock: use BigCommerce webhooks to trigger a OneSignal API call when product stock transitions from 0 to available
5. For cart abandonment: use BigCommerce's Abandoned Cart webhook + OneSignal REST API to send cart recovery pushes

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Custom / Headless

For headless stores, implement push using the Web Push API directly:

// Service worker — save as /sw.js in your public directory
self.addEventListener('push', (event) => {
  const data = event.data?.json() ?? {};
  event.waitUntil(
    self.registration.showNotification(data.title, {
      body: data.body,
      icon: data.icon ?? '/icons/icon-192.png',
      image: data.image,
      data: { url: data.url },
      actions: data.actions ?? [],
    })
  );
});

self.addEventListener('notificationclick', (event) => {
  event.notification.close();
  event.waitUntil(clients.openWindow(event.notification.data?.url ?? '/'));
});

// Server-side push sending using the web-push library
import webpush from 'web-push';

webpush.setVapidDetails(
  'mailto:[email protected]',
  process.env.VAPID_PUBLIC_KEY!,
  process.env.VAPID_PRIVATE_KEY!
);

// Generate VAPID keys once: npx web-push generate-vapid-keys

async function sendPushNotification(subscription: PushSubscription, payload: {
  title: string;
  body: string;
  url: string;
  icon?: string;
}) {
  try {
    await webpush.sendNotification(subscription, JSON.stringify(payload));
  } catch (err: any) {
    if (err.statusCode === 410) {
      // Subscription expired — remove from database
      await db.pushSubscriptions.deleteByEndpoint(subscription.endpoint);
    }
  }
}

// Triggered when inventory transitions from 0 to > 0
async function notifyBackInStock(productId: string) {
  const product = await db.products.findById(productId);
  const waitlist = await db.pushWaitlist.findByProduct(productId);

  for (const entry of waitlist) {
    const sub = await db.pushSubscriptions.findByUserId(entry.userId);
    if (!sub) continue;
    await sendPushNotification(sub, {
      title: 'Back in stock!',
      body: `${product.name} is available again`,
      url: `${process.env.STORE_URL}/products/${product.slug}`,
      icon: product.images[0]?.url,
    });
  }
}

Step 3: Optimize opt-in timing

The most critical factor for push notification effectiveness is when you show the permission prompt. Never ask on the first page load.

Best triggers for the opt-in prompt:

• After the visitor has viewed 3+ products
• Immediately after a customer adds an item to cart
• When a customer views an out-of-stock product (context: "Get notified when it's back")
• On the order confirmation page ("Get shipping updates and deals via browser push")

In PushOwl: go to Settings → Opt-in Prompt → Advanced and set the trigger condition. In PushEngage: go to Subscription Prompt → Display Rules and set page view count or cart event triggers.

Step 4: Set up the highest-converting push campaigns

Priority order by conversion rate:

1. Back-in-stock alerts — highest CTR (15–25%); customers opted in specifically for this product
2. Cart abandonment — set for 1 hour and 24 hours after abandonment; use urgency in the second push ("Your cart expires soon")
3. Price drop alerts — customers watching a specific product convert at 10–20% when notified of their target price
4. Shipping updates — low-friction way to grow push subscribers (capture at order confirmation); keeps brand top-of-mind

In PushOwl: all four are available as pre-built automations under Automations — enable them and customize the message.

Step 5: Measure push performance

| Metric | Healthy Target | Where to Find | |--------|----------------|---------------| | Opt-in rate | 5–15% of new visitors | App dashboard | | Back-in-stock click rate | 15–25% | PushOwl/PushEngage analytics | | Cart abandonment recovery rate | 2–5% | App analytics | | Unsubscribe rate per campaign | < 2% | App analytics |

If unsubscribe rate is above 2%, reduce push frequency or improve message relevance.

Best Practices

• Never request permission on first page load — acceptance rates jump from ~5% to ~25% when shown after a user action like adding to cart
• Limit to 2 push notifications per day per user maximum — excessive frequency is the top driver of opt-out
• Set a TTL on time-sensitive notifications — flash sale pushes should expire when the sale ends; PushOwl and PushEngage both support notification expiry
• Keep notification body under 100 characters — longer bodies are truncated on Android; test on mobile before deploying
• Use "Notify me" at the product level for out-of-stock — this captures high-intent subscribers with context; generic sitewide opt-ins perform worse

Common Pitfalls

| Problem | Solution | |---------|----------| | Low opt-in rate | Move the permission prompt to after add-to-cart or product view #3; never show on first load | | iOS users not receiving push | Web push on iOS requires iOS 16.4+ and the user must install the site as a PWA (Add to Home Screen); this is a browser limitation | | Push notifications not firing for back-in-stock | Verify the inventory webhook is connected in PushOwl/PushEngage settings; check the app's automation logs | | High unsubscribe rate | Reduce push frequency; add preference management so subscribers can choose which notification types they receive | | Duplicate subscriptions in the database | For custom implementations, use upsert keyed on (userId, endpoint) |

Related Skills

• @email-marketing-automation
• @cart-abandonment-recovery
• @sms-marketing
• @exit-intent-popups
• @customer-retention-engine