The best Shopify back in stock notification apps turn "Sold Out" dead ends into revenue recovery machines. A customer picks a size, hits "Add to Cart," and sees "Sold Out." Without a notification app, they leave and never come back. With one, they sign up and get an automatic alert when inventory returns.
These alerts perform far better than standard marketing emails. According to Omnisend's 2025 benchmark data, back-in-stock emails achieved 58% open rates and over 6% conversion rates. That makes them one of the highest-performing automated flows in ecommerce.
The difference between losing a sale forever and recovering it later is one button. Here are the seven best Shopify apps that add it.
How Do You Choose a Back in Stock Notification App?
Five factors separate a good back in stock app from one that collects dust:
- Notification channels — Email is the baseline. SMS catches customers who ignore email. WhatsApp matters if you sell in MENA, South Asia, or Latin America. Push notifications work for repeat visitors.
- Free tier limits — Most apps offer a free plan, but the notification caps vary wildly. Some give you 10/month, others give you 500.
- Preorder support — Several apps bundle preorder functionality with back-in-stock alerts. If you want both, you can avoid paying for two separate apps.
- Integrations — Klaviyo, Mailchimp, and Omnisend integrations let you build restock alerts into your existing email flows instead of running a separate system.
- Customization — The "Notify Me" button should match your theme. The signup form should support your store's languages.
Back In Stock, Notify Me: Kbite — Best Free Plan for Small Stores
Rating: 5.0/5 (3,482 reviews) | Free plan: 30 emails/month, unlimited subscribers | Paid: From $5/month
Kbite has the most reviews and the highest rating in this category, which usually means one thing: it works and the support team responds. The free plan gives you 30 emails/month with unlimited subscriber signups — meaning you can collect waitlist demand even before upgrading.
Paid plans start at just $5/month for 500 emails, making it the cheapest option for stores that need more volume. It supports email and SMS alerts, price drop notifications, multi-language forms, and syncs with your mailing list. It carries the "Built for Shopify" badge, which means Shopify has vetted it for performance and integration standards.
Best for: Small to mid-size stores that want a reliable, affordable back-in-stock solution without paying for features they don't need.
STOQ: Preorder, Back In Stock — Best for Combined Preorders and Restock Alerts
Rating: 5.0/5 (2,981 reviews) | Free plan: 10 preorders, 30 emails/month | Paid: From $10/month
STOQ bundles preorder management with back-in-stock notifications, which makes it a strong pick if you want both features in a single app. The preorder side supports partial payments and deposits — customers pay upfront and get the product when it ships. The back-in-stock side handles waitlists and automatic email/SMS alerts when inventory returns.
It integrates with Klaviyo, Mailchimp, and Omnisend, supports 23+ languages, and works with Shopify POS and Shopify Flow. The free plan is limited (10 preorders, 30 emails), but the $10/month Lite tier unlocks 100 preorders and 1,000 notifications.
Best for: Stores that regularly sell out and want to capture revenue through preorders while also alerting customers when regular stock returns.
Notify! Back in Stock | PreOrder — Best for Wishlists and Low-Stock Alerts
Rating: 4.9/5 (3,068 reviews) | Free plan: 10 notifications, 5 preorders | Paid: From $9.90/month
Notify! goes beyond basic restock alerts by adding wishlist functionality and low-stock triggers. Customers can save products to a wishlist, and you can send alerts when inventory drops below a threshold — creating urgency before products sell out completely.
It supports email, SMS, and web push notifications, integrates with Klaviyo and Mailchimp, and works with Shopify Checkout and POS. The free plan is tight (10 notifications), but the Kickstart plan at $9.90/month opens things up. Annual billing saves roughly 20%.
Best for: Stores that want a full demand-capture toolkit — wishlists, low-stock urgency, preorders, and restock alerts in one app.
Amp Back in Stock | PreOrder — Best for Push Notification Support
Rating: 4.9/5 (841 reviews) | Free plan: 10 notifications | Paid: From $19/month
Amp is one of the oldest back-in-stock apps on Shopify, launched in 2011. It's also one of the few that supports web push notifications alongside email and SMS. Push notifications don't require an email address — customers just click "Allow" in their browser. That can increase signup rates for privacy-conscious shoppers.
The app also offers preorder and pre-sale functionality, real-time analytics on restock performance, and integrations with Klaviyo, Mailchimp, Zapier, and Shopify Flow. The downside: it's pricier than alternatives. The free plan caps at 10 notifications, and paid plans start at $19/month for just 50 notifications.
Best for: Established stores with significant traffic that want to capture demand through push notifications without requiring email signups.
Stok: Back in Stock Alert — Best for WhatsApp Restock Alerts
Rating: 4.7/5 (113 reviews) | Free plan: Yes (limited) | Paid: From $10/month
Stok stands out because it supports WhatsApp notifications alongside email and SMS — starting from the $10/month Plus plan. If you sell in markets where WhatsApp is the dominant communication channel (most of MENA, South Asia, Latin America), reaching customers on WhatsApp instead of email can dramatically improve alert open rates.
The app also handles price drop alerts and sales notifications, not just restocks. It supports 23 languages and includes preorder functionality. The free plan is limited (no email notifications included), so most stores will need the $10/month tier at minimum.
Best for: Stores selling in emerging markets where WhatsApp is the primary messaging channel and email open rates are low.
Back In Stock | Restock Alerts by Crawlapps — Best Budget Option With WhatsApp
Rating: 5.0/5 (17 reviews) | Free plan: 100 emails/month | Paid: From $4.99/month
Crawlapps offers the most generous free plan in this category: 100 email alerts/month, unlimited subscribers, customizable button and templates, and multi-language support — all at $0. The $4.99/month Starter plan adds SMS and WhatsApp alerts, Klaviyo integration, and 500 emails.
The review count is low (17 reviews), so it hasn't been battle-tested at scale like Kbite or STOQ. But if you're a smaller store looking for a budget-friendly option that includes WhatsApp support, it's hard to beat $4.99/month.
Best for: New or small stores that need a free back-in-stock solution with room to grow into WhatsApp and SMS alerts affordably.
Appikon — Back In Stock — Best for High-Volume Email Campaigns
Rating: 4.7/5 (1,405 reviews) | Free plan: 10 emails/month | Paid: From $19.99/month
Appikon has been around for a while and has a solid track record with over 1,400 reviews. Its strength is email-focused restock campaigns with detailed analytics on subscriber demand and conversion performance. It integrates with Mailchimp, Klaviyo, and Zapier, and supports multi-language stores.
The pricing is on the higher side — $19.99/month for the Starter plan — and the free plan is very limited at 10 emails/month. SMS is available but charged separately ($0.05–$0.40 per message). Annual billing saves 20%.
Best for: Mid-size to larger stores that run frequent restocks and want detailed analytics on waitlist demand and notification performance.
Quick Comparison Table
| App | Rating | Free Plan | Paid From | SMS | Push | Preorders | ||
|---|---|---|---|---|---|---|---|---|
| Kbite | 5.0 (3,482) | 30 emails/mo | $5/mo | Yes | Yes | No | No | No |
| STOQ | 5.0 (2,981) | 30 emails/mo | $10/mo | Yes | Yes | No | No | Yes |
| Notify! | 4.9 (3,068) | 10 notifs/mo | $9.90/mo | Yes | Yes | No | Yes | Yes |
| Amp | 4.9 (841) | 10 notifs/mo | $19/mo | Yes | Yes | No | Yes | Yes |
| Stok | 4.7 (113) | Limited | $10/mo | Yes | Yes | Yes | No | Yes |
| Crawlapps | 5.0 (17) | 100 emails/mo | $4.99/mo | Yes | Yes | Yes | Yes | No |
| Appikon | 4.7 (1,405) | 10 emails/mo | $19.99/mo | Yes | Yes | No | No | No |
Which Back in Stock App Should You Pick?
If you're just starting out and want the best free plan, Kbite gives you 30 emails/month with unlimited subscribers at $0 — and scales to $5/month when you need more. If you also need preorder functionality, STOQ bundles both into one app starting at $10/month.
If you sell in markets where WhatsApp is the default messaging channel, Stok or Crawlapps are your best options — both support WhatsApp alerts starting from their cheapest paid plans.
If you want to capture signups without requiring an email address, Amp and Notify! both support web push notifications. Amp has more experience (15 years on the App Store), while Notify! adds wishlists and low-stock urgency triggers.
Every out-of-stock product page without a "Notify Me" button is a customer you'll never see again. Pick any app from this list, install it today, and start turning stockouts into a waitlist that converts when inventory comes back. If you're also looking to optimize your order flow and reduce cart abandonment, check out our guide to setting up abandoned cart recovery on Shopify.