A shopper finds the exact product they want, picks a size, and sees “Sold out.” Many will buy from a competitor or simply forget. Every sold-out page with no next step is demand you paid to create and then threw away.

Back-in-stock and pre-order apps give that shopper a next step. A restock alert collects an email or phone number and messages the shopper the moment inventory returns. A pre-order tool goes further and takes the order, and sometimes the payment, before the stock arrives. Both turn a dead end into either a lead or a sale.

Below, we compare five well-known options for Shopify and WooCommerce stores, explain the difference between restock alerts and pre-orders, and cover two details that trip up many stores: inventory sync and when the customer’s card is actually charged. If your sold-out problem is really a stock-planning problem, also see our guide to the best inventory management software.

Editorial note: this article contains no affiliate links. Prices and features were checked against each vendor’s official pages on November 8, 2026, and we have not hands-on tested these tools. Vendors change plans often, so confirm current pricing before you buy.

Why Sold-Out Pages Cost More Than You Think

IHL Group, a retail research firm, estimates that inventory distortion (the combined cost of out-of-stocks and overstocks) would cost retailers worldwide $1.77 trillion in 2023. The same study found out-of-stocks in North America rose 17.7% that year. A sold-out product page still collects traffic from ads, search and email, and without a restock alert or pre-order option that traffic leaves with nothing captured.

Shoppers who ask to be told when an item returns have already shown purchase intent, which is why automated messages like these tend to outperform general promotions. Restock alerts also pair well with cart abandonment recovery software, since both target shoppers who were close to buying.

Restock Alerts vs Pre-Orders: What Is the Difference?

A back-in-stock alert (also called a notify-me or waitlist button) replaces the disabled “Add to cart” button with a sign-up form. No order is created and no money changes hands. When inventory returns, the app emails or texts subscribers, and they buy at full price through your normal checkout. Use this for products you restock regularly and where you do not know the exact arrival date.

A pre-order lets the shopper place a real order for an item that is not in stock yet. You need a clear ship date, a policy for delays, and a decision on payment capture: charge in full now, take a deposit, or charge later when the item ships. Use this for new launches, limited drops, made-to-order products and items with a confirmed incoming shipment.

Many stores use both: pre-orders when a delivery date is confirmed, and restock alerts when it is not.

1. Klaviyo — Best for Stores Already on Klaviyo

Best for: Shopify and BigCommerce stores that already send email or SMS through Klaviyo and want restock alerts without adding another app.

What Klaviyo does well

• Back in stock is a built-in flow. Shopify and BigCommerce stores can add the sign-up form with Klaviyo’s form builder; Magento 2, PrestaShop, Salesforce Commerce Cloud and Shopware use a theme snippet.
• A restock minimum controls how many units must be in stock before alerts go out, so a single returned item does not trigger hundreds of emails.
• Advanced settings send alerts in batches per restocked unit, which helps avoid notifying more people than you can sell to.

Potential drawbacks

• WooCommerce is not on Klaviyo’s list of supported platforms for the built-in back-in-stock feature, so Woo stores need a custom catalog or API setup, or a different tool.
• It handles alerts only. There is no pre-order or payment capture feature.
• Cost grows with your active profile count, and restock sign-ups add profiles.

Pricing

Free plan: up to 250 active profiles and 500 emails per month, plus $5 of mobile messages per month. Email plan: from $20/month for 500 active profiles and 5,000 emails per month. SMS is an add-on to paid plans. Prices rise with list size, so check the calculator for your profile count. Source: Klaviyo pricing page, checked November 8, 2026.

See Klaviyo Pricing →

2. Appikon Back In Stock — Best Dedicated Restock Alert App for Shopify

Best for: Shopify stores that want a focused restock alert and waitlist app, with email and SMS, without changing their email platform.

What Appikon Back In Stock does well

• Sends automatic back-in-stock notifications and back-order reminders by email and SMS, with sign-up forms that work across themes.
• Shows demand analytics by product, which helps you decide what to reorder first.
• Paid plans integrate with Klaviyo and Mailchimp, and the app also lists PushOwl, Wiser and Zapier integrations. It holds a 4.8 rating from 1,458 reviews on the Shopify App Store.

Potential drawbacks

• The free plan includes only 10 emails per month, which is a trial in practice.
• Plans cap monthly emails, so a large waitlist on a popular product can push you up a tier.
• SMS is charged per message on every plan, and it does not take pre-orders.

Pricing

Free: 10 emails/month. Starter: $19.99/month or $192/year, 300 emails/month. Pro: $29.99/month or $287.90/year, 1,000 emails/month, adds collection page integration. Premium: $49.99/month or $479.90/year, 3,000 emails/month. SMS costs $0.05 to $0.40 per message. Paid plans include a 7-day free trial. Source: Appikon Back In Stock Shopify App Store listing, checked November 8, 2026.

See Appikon Plans →

3. PreProduct — Best for Flexible Pre-Order Payments on Shopify

Best for: Shopify brands running product launches or crowdfunding-style pre-orders that need control over when and how customers pay.

What PreProduct does well

• Lets you charge upfront, charge later using a vaulted card, or take a deposit, which solves the payment timing problem described below.
• Includes customer portals, customizable email campaigns and unlimited listings and pre-orders on every plan.
• The Scale plan adds Shopify Flow triggers and actions, more than 10 Klaviyo events and API access for stores that want automation.

Potential drawbacks

• The free Starter plan charges a 5% transaction fee on paid pre-order revenue, which adds up quickly on a big launch.
• Scale starts at $99.99/month, a big step up for small stores.
• Instalment plans are marked as Shopify Plus only.

Pricing

Starter: free to install, plus a 5.0% fee on paid pre-order revenue. Scale: $99.99/month, 0% commission on up to 5k of monthly paid pre-order revenue and 0.5% above that (the listing does not state the currency). Scale Plus: $259.99/month, 0% commission, recommended for Shopify Plus. Scale and Scale Plus include a 7-day free trial. Source: PreProduct Shopify App Store listing, checked November 8, 2026.

Check PreProduct Pricing →

4. Timesact — Best Budget Pre-Order and Notify-Me App on Shopify

Best for: Small Shopify stores that want pre-orders and back-in-stock alerts in one inexpensive app.

What Timesact does well

• Combines pre-orders, a notify-me button and back-in-stock emails, so one app covers both sold-out scenarios.
• Paid plans support split payments, deposits and zero-down pre-orders, and the PRO plan can charge on fulfillment.
• The free plan includes unlimited emails and a Klaviyo integration, and the app holds a 5.0 rating from 2,137 reviews on the Shopify App Store.

Potential drawbacks

• The free plan is limited to 20 pre-orders per month and shows Timesact branding.
• Flex plans charge per order above the included limit, so costs vary with volume.
• Storewide automatic back-in-stock and low-stock alerts are on PRO, not the cheaper plans.

Pricing

Free (new users): 20 orders/month. CORE Flex: from $5/month with 10 extra orders, then $0.20 per order. PRO Flex: from $7/month with 10 orders, then $0.30 per order. CORE Fixed: $23/month or $204/year with unlimited orders for CORE features. SMS costs extra. Source: Timesact Shopify App Store listing, checked November 8, 2026.

See Timesact Plans →

5. YITH Pre-Order for WooCommerce — Best for WooCommerce Pre-Orders

Best for: WooCommerce stores that want pre-orders with release dates, and the option to charge customers on release.

What YITH Pre-Order does well

• The free version on WordPress.org lets you set products to pre-order, set a release date that ends pre-order mode automatically, adjust the pre-order price and email the admin and customer.
• Premium can switch out-of-stock products to pre-order automatically, so sold-out items keep taking orders.
• Premium adds a “Pay Later” option and automatic charging on release through supported gateways, plus user-role limits and extra notifications.

Potential drawbacks

• Automatic charging on release needs a supported gateway plugin such as YITH Stripe or YITH Braintree, which is sold separately.
• The free version charges customers when they place the pre-order, with no deferred payment.
• The free plugin has a 3.1 rating from 16 reviews on WordPress.org, so test it on staging first.

Pricing

A free version is available on WordPress.org (6,000+ active installs). We could not confirm the premium license price from the official product page, which did not display it in our check, so view yithemes.com for the current price. Source: WordPress.org plugin page and YITH product page, checked November 8, 2026.

Check YITH Pre-Order Pricing →

Shopify vs WooCommerce: Inventory Sync and Payment Timing

Inventory sync. Restock alerts only work if the app sees inventory change when it happens. On Shopify, apps read stock from Shopify itself, so alerts fire when you update quantities or receive a transfer. If stock lives in a warehouse system or ERP, make sure it pushes quantities to your store promptly, or alerts go out late. For pre-orders, set a cap on how many units you sell so you do not take more orders than your incoming shipment covers.

Payment capture timing. This matters most for pre-orders. Shopify Payments gives an authorization period of 7 days, so you cannot simply authorize a card at checkout and capture it a month later when the item ships. Shopify Plus stores get extended authorization of up to 30 days on Visa, Mastercard and American Express, and Shopify applies an extra 1.75% charge when you capture after the standard 7 days. For longer lead times, use a tool that saves the card and charges later (PreProduct, Timesact’s charge-on-fulfillment option) or one that takes a deposit. On WooCommerce, YITH’s charge-on-release feature depends on a supported gateway plugin.

Back-in-Stock and Pre-Order Apps Compared Side by Side

Which Back-in-Stock or Pre-Order Tool Is Right for You?

Use this decision path to narrow it down in about a minute.

What to Look for in Back-in-Stock and Pre-Order Apps

• Platform fit. Shopify apps will not run on WooCommerce, and some features, such as instalments or extended authorizations, are limited to Shopify Plus.
• Payment options. For pre-orders, check whether the tool supports full upfront, deposit and charge-later payments, and which gateways it needs.
• Channels. Email is standard. SMS can perform well for restocks but is usually billed per message, so compare it with your SMS marketing software.
• Inventory controls. Look for restock minimums, batch sending, pre-order caps and automatic switching between pre-order and in-stock modes.
• Total cost. Include transaction fees, per-order overages and email or SMS caps, not just the monthly price.

Quick Wins You Can Make Before Buying Anything

1. Keep sold-out pages live. Do not unpublish or redirect products that will return. They keep their search rankings and can collect sign-ups.
2. Show an expected date. Even a rough “back in early December” note keeps more shoppers interested than a bare “Sold out.”
3. Suggest alternatives. Link to similar in-stock products on the sold-out page.
4. Write a pre-order policy. State the ship date, when the card is charged and how cancellations work before you take a single order.
5. Check your stock sync. Confirm that quantities from your warehouse or supplier update in your store at least daily.

Frequently Asked Questions

What is a back-in-stock app?

It replaces the disabled add-to-cart button on a sold-out product with a sign-up form, then emails or texts subscribers automatically when inventory returns.

What is the difference between a pre-order and a back order?

A pre-order is usually for a product that has not been released or delivered yet, with a set ship date. A back order is an order for an existing product that is temporarily out of stock. Many apps handle both the same way.

When should I charge customers for a pre-order?

If the item ships within a few days, charging upfront is simplest. For longer waits, a deposit or charge-later option lowers the risk of refunds and disputes. On Shopify Payments, card authorizations last 7 days by default, so plan for that.

Can I use Klaviyo back in stock with WooCommerce?

Klaviyo’s help center does not list WooCommerce among the platforms supported for its built-in back-in-stock feature. Stores can use a custom catalog or API setup, which needs developer work.

Are pre-orders legal?

Yes, but consumer rules apply. In the US, the FTC’s Mail, Internet, or Telephone Order Merchandise Rule says you need a reasonable basis for any ship date you state, or for shipping within 30 days if you state none. If you miss it, you must tell the customer, give a revised date and explain their right to cancel for a full refund. Check the rules for every market you sell to.

Do restock alerts work better by email or SMS?

Both can work. Klaviyo reported one client converting at 7.9% by email and 8.5% by SMS on back-in-stock messages, but that is a single example. Test both with your own audience.

How much do back-in-stock and pre-order apps cost?

Among the tools above, all offer a free entry point. Paid plans start at $5/month (Timesact) and $19.99/month (Appikon), while PreProduct’s Scale plan is $99.99/month.

Do I need a developer to set this up?

Most of these tools are built for merchants to configure themselves. If you need custom pre-order logic, theme changes or inventory integrations, our Shopify development and WooCommerce development services can help.

Final Verdict: Which Back-in-Stock or Pre-Order App Should You Choose?

If you already run Klaviyo on Shopify, start with its built-in back-in-stock flow. If you want a dedicated restock alert app, Appikon Back In Stock is a focused Shopify option. For pre-orders on Shopify, choose PreProduct when payment flexibility matters most, or Timesact when budget matters most and you want notify-me alerts in the same app. On WooCommerce, YITH Pre-Order for WooCommerce lets you start free and upgrade when you need charge-on-release.

Your next step: list your top five sold-out products by traffic, add a restock alert or pre-order option to them first, and compare recovered revenue after 30 days. Fixing the pages that already get visitors pays off fastest.

Sources

• Retail TouchPoints: IHL study on inventory distortion in 2023
• Klaviyo 2026 email marketing benchmarks
• Klaviyo: How back-in-stock SMS messages turn waitlists into revenue
• Klaviyo Help Center: How to build a back in stock flow
• Klaviyo pricing
• Appikon Back In Stock on the Shopify App Store
• PreProduct on the Shopify App Store
• Timesact on the Shopify App Store
• YITH Pre-Order for WooCommerce on WordPress.org
• YITH Pre-Order for WooCommerce product page
• Shopify Help Center: Payment authorization
• FTC: Selling on the Internet, prompt delivery rules

About the author

Jaykishan Panchal

Founder & CEO, TechCognate · SEO Strategist & WordPress Expert

Jaykishan Panchal is the founder of TechCognate and an SEO strategist with 15+ years of hands-on experience driving organic growth for businesses worldwide. He specialises in technical SEO, content strategy and GEO (Generative Engine Optimisation), helping brands stay visible in both traditional search and AI-driven discovery.

• Technical SEO
• Content Strategy
• AI & GEO
• Google Ads
• E-Commerce SEO

LinkedInX / @TechCognateAll articles