Usage

The widget appears on the product page under the buy buttons (products:product_detail_bottom hook). It loads by AJAX after the page, so cached pages stay correct for every visitor.

What the shopper can choose depends on the product:

Product state	Offered alerts
Out of stock (stock tracked, quantity 0 or less)	It is back in stock (pre-selected, form open) and The price drops
In stock, quantity above the low-stock threshold	The price drops (pre-selected) and Only a few are left
In stock, quantity at or below the threshold, or stock not tracked	The price drops
Disabled or hidden product	nothing

Products with a price of 0 never offer the price-drop alert.

Target price (optional): “Only when the price falls to …” in the currency the shopper sees. It must be lower than the current price.
E-mail: guests type it; logged-in customers see “Alerts go to …” with their account e-mail.
After subscribing, the widget lists the active alerts with a Stop button each. Pending alerts show “confirm by e-mail”.
Variations: each variation is a product of its own, so alerts are per variation. Switching the variation reloads the widget for it.

A hidden honeypot field and a limit of 10 subscribe requests per 10 minutes per visitor keep bots out.

When alerts fire

Alert	Fires when	Afterwards
Back in stock	The product is active and its stock is above 0 (or stock tracking is off).	Finished.
Low stock	The product is active and its stock is between 1 and the threshold.	Finished.
Price drop	The product is active and in stock, the price is lower than the reference price by at least Minimum price drop, and at or below the target price if one was set.	Without target: keeps watching from the new price (setting Keep watching). With target: finished.

The reference price is the price when the shopper subscribed (the guest price for quantity 1, after catalog promotions when that setting is on). If the price drops while the product is out of stock, the alert fires as soon as it is back in stock and still cheaper.

Changes are detected:

right away when a product is saved in the admin panel, the vendor panel or through the API, when stock changes because of an order, a return or a warehouse update, when the bulk price update runs, and when a product status is toggled in the list;
within a few runs for everything else (imports, direct database changes, catalog promotions starting or ending), through the rolling re-check.

The send queue

Fired alerts go to the queue, one row per channel. A run sends at most Messages per run rows; failed rows are retried up to 3 times and then marked failed with the error.

The demand report, the subscription list and the queue show the license status at the top: a small License: Valid chip, or a banner with the status and the actions when the add-on is switched off (see License).

Products → Stock & price alerts → Send queue shows the counters, the last 50 rows with their status and errors, the last run, and recent internal errors. Buttons:

Process queue now: run immediately (ignores Minutes between runs);
Retry failed messages (gear menu): put failed rows back in the queue;
Clear the error log (gear menu).

Alerts of a shopper who unsubscribed before the run are cancelled, not sent.

Demand report

Products → Stock & price alerts opens the demand report.

The tiles at the top show open back-in-stock requests (including the core “Notify me” list), price watchers, low-stock watchers, alerts sent in the last 30 days, and orders (with revenue) placed by notified shoppers for the notified product within 30 days after an alert, over the last 90 days.

The table lists every product with alerts:

Column	Meaning
Stock	Current quantity; out-of-stock rows are marked and highlighted.
Price	Current watched price.
Waiting for restock	Open back-in-stock alerts plus core “Notify me” subscriptions.
Price watchers	Open price-drop alerts.
Target price	Lowest and average target price shoppers entered.
Low-stock watchers	Open low-stock alerts.
Notified	Alerts already sent for the product.
Last request	Date of the newest subscription.

Sort by any underlined column, search by name or code, and tick Only out-of-stock products to get a purchasing list. In Ultimate, selecting a storefront in the admin panel limits the report to that storefront’s subscribers.

Subscriptions lists every alert with the e-mail address, product, type, reference and target price, channels, dates and status. Filter by e-mail, type and status; unsubscribe or delete selected rows from the gear menu.

Multi-Vendor

Vendors find Products → Stock & price alerts in the vendor panel. It shows the demand report for their own products only, without the subscriber list, the queue or any shopper e-mail address.
The marketplace administrator sees all products, with the vendor name under each product.
Alert e-mails are sent from the marketplace (company 0) settings and mailer.

Shopper self-service

Every alert e-mail has Stop this alert, Stop all alerts and Manage alerts links. They work without logging in.
My stock & price alerts (index.php?dispatch=kv_price_stock_alerts.manage) lists the alerts with their status and a Stop button. Logged-in customers reach it from the account menu.