A Notify me button is simple, but small implementation details decide whether shoppers actually use it.
Place it near the buy buttons
The best location is directly under or near the add-to-cart area. That is where shoppers already look for the next purchase action. If the product is unavailable, the notify action should replace uncertainty with a clear next step.
Keep the copy specific
Use copy such as "Notify me when available" or "Email me when this variant is back". Avoid vague text that does not explain what will happen after signup.
Respect variant selection
For products with sizes, colors, bundles, or other variants, the signup must follow the selected variant. Variant-level accuracy is one of the biggest differences between a useful restock tool and a frustrating one.
Ask for the minimum information
Email is usually enough for launch. Browser push can be offered as an explicit option, but permission prompts should never appear automatically on page load.
Confirm success clearly
After signup, show a short success message that tells the shopper they will be notified when the product returns. This prevents duplicate submissions and builds trust.
See the Bodanu widget setup guide for a Shopify implementation that supports wishlist and notify actions near the product buy buttons.