Product stock-outs are common. That’s why most Shopify stores have automated back-in-stock alerts set up to bring back lost customers.
While a common choice for setting up these alerts is Klaviyo, most merchants struggle to set up workflows that drive conversions from these notifications.
That’s why in this post, we’re going to discuss:
- What Klaviyo’s back-in-stock feature can (and can’t) do
- Why merchants are switching to STOQ
- A side-by-side comparison of Klaviyo vs STOQ
- Other alternatives worth considering
Klaviyo back in stock alerts refers to the automated notifications merchants can set up via email to bring back potential customers lost to product stock-outs. The CRM solution built offers a back in stock feature that integrates with Shopify, enabling the following:
- Adding a “Notify Me” form to out-of-stock product pages
- Capturing shopper emails
- Sending a back-in-stock email once inventory is available
While setting up back in stock alerts on Klaviyo is pretty simple and easy, the feature lacks the depth required to convert customers lost to product stockouts. Here’s why:
Klaviyo doesn’t support SMS for back-in-stock alerts. This limits your ability to reach customers via a commonly used channel, which also has proven to deliver higher open and click-through rates as compared to emails.
You can’t customize alerts based on warehouse location or restock timelines on Klaviyo. These are critical for online stores using Shopify’s multi-location inventory setup, leading to loss of data and inability to manage consumer demand.
You can’t control how often alerts go out or set batch sizes. This means one restock might flood thousands of inboxes, creating a poor customer experience. In the long run, this can lead to losing out on the subscriber list you have built.
Merchants have reported that Klaviyo struggles with tracking inventory at the variant level (e.g. size, color), often leading to misfired alerts. This can result in consumers losing interest in the stocked out items.
The back-in-stock alert signup form is basic and often doesn’t match the site’s design or UX needs. If you require customizing it further to match your store’s look and feel, or follow a different workflow, you need a developer for the same.
STOQ is a Shopify-native app designed specifically to address product stockouts. It comes with advanced features to fix these gaps in back-in-stock and preorder functionality. It gives you everything Klaviyo’s features are missing - and more. Here’s why you see most brands switching to STOQ for back-in-stock alerts:
STOQ enables you to set up restock notifications through both email and SMS. This gives consumers the choice to choose a preferred channel, ensuring your alerts don’t get buried under the noise. The multiple touchpoints also help ensure your brand remains top of the mind in competitive markets.
STOQ can track restocks down to the variant level of your inventory - size, color, material or any other option. This ensures that online shoppers get alerts only for the specific variant requested and not just the product in general. The feature doesn’t just help ensure relevancy of the restock notification, but also improves overall customer satisfaction levels.
You can control how many notifications are sent out when a product gets restocked using STOQ. The app offers intelligent throttling and batching, which enables sending alerts in controlled batches based on inventory levels. This gives you predictable conversion rates and ensures a better customer experience.
With STOQ, you can fully customize the back-in-stock signup widget. This includes the change in text, button design, placement and more - all without writing a single line of code. The consistent brand experience leads to better UX, higher opt-ins and more recoverable revenue.
STOQ supports Shopify’s multi-location inventory. This means it can handle automation of back-in-stock alerts based on specific warehouses, fulfillment centers or regions. For brands selling globally or managing inventory across different locations, this helps prevent customer confusion or frustration - especially when an item is restocked in one region but is not available for shipping to another.
Another reason why merchants switch to STOQ from Klaviyo is its analytics and insights. The dashboard gives you a clear view of stocked-out products, the number of signups across channels, notifications sent out and the sales they resulted in. This helps brand understand consumer demand better and forecast their market growth.
Explore STOQ on the Shopify App Store.
Here’s a quick feature-wise comparison of STOQ and Klaviyo back-in-stock alerts:
Klaviyo’s major focus is on building a CRM for e-commerce businesses. So while it does offer back-in-stock alerts as a feature, it may not be enough for fast-moving brands. The feature is more suited for stores that:
- Sell single-variant products
- Rely only on email
- Don’t need multi-location or multichannel logic
While STOQ is the best Shopify back-in-stock alerts app, here are a few other alternatives that you can consider:
1. Back in Stock by SureSwift Capital
- Reliable and established - One of the earliest players in the space.
- Limited SMS support - Primarily focused on email notifications.
- Basic analytics - Lacks deep insights or reporting on alert performance.
- Best for - Stores that want a no-frills, email-first approach and don’t require a ton of customization.
2. Appikon Back in Stock Alerts
- Variant-level alerts - Tracks size, color, and other product options individually.
- Limited multi-location support – Not always accurate if you run multiple warehouses.
- Rigid UI options - Customization of the “notify me” button and popups can be limited.
- Best for - Merchants who need core functionality at a low cost but are okay with less flexibility.
- Enterprise-focused - Includes wishlist, pre-order, and other engagement tools.
- Feature-rich but complex - Powerful, but takes time to set up and configure.
- On the pricier side - Pricing can be less transparent and scales up quickly.
- Best for - Larger Shopify Plus brands looking for a robust suite, not just back-in-stock alerts.
4. CartBite
- Multi-channel - Supports push notifications in addition to email/SMS.
- Broad focus - Offers several features beyond just BIS alerts.
- Less refined UX - Not as focused or clean as STOQ for back-in-stock-specific needs.
- Best for - Stores wanting a wider toolkit under one app, even if it’s not laser-focused on BIS alerts.
5. Timesact Pre-order & Back in Stock
- Flexible pre-order setup – Ideal if you're often out of stock but want to keep sales open.
- BIS features are secondary – Not as advanced or granular as STOQ.
- Good UI design – Clean, modern user experience for buyers.
- Best for - Brands that prioritize pre-orders over BIS alerts, but still want basic functionality.
Looking for more alternatives? Here are the best Shopify back-in-stock apps.
With Harvard Business Review reporting nearly $1 trillion in sales lost annually to product stock outs, businesses need to be better prepared. That’s where choosing the right solution to automate back in stock alerts comes in.
If you have been using Klaviyo’s back in stock alerts and struggling to drive conversions, it’s time to switch to STOQ.
Can I use Klaviyo and STOQ together?
Yes. STOQ can handle the back-in-stock alerts while you continue using Klaviyo for other marketing campaigns. The two automated workflows can work in tandem without compromising on the customer experience.
Does STOQ support preorders too?
Absolutely. STOQ also lets you sell out-of-stock items as pre-orders, helping you never miss a sale.
Is STOQ difficult to set up?
Not at all. Most merchants get started in under 10 minutes - with no developer help needed. If you’re switching from Klaviyo to us, we also offer assistance in migrating your data and setting up the workflows so that your customers don’t experience broken interfaces.