Feature · Stock & restock
Know the moment a competitor sells out - or restocks
First, to be clear: this tracks a COMPETITOR's stock - when a rival sells out or restocks - not sending your own customers 'back in stock' emails (that's a different kind of app). Stock movements are some of the most actionable competitor signals there are: when a rival sells out, it's your window to capture demand; when they restock a hot item, you'll want to know immediately. Shop Sentry watches availability on every product and variant of any store you add, and alerts you the moment it flips.
Stock signals you'll catch
Sell-outs
Get alerted when a competitor's product - or a specific size/color - goes out of stock, so you can capture the demand.
Restocks
Know the instant a sold-out item comes back, including which variants returned.
Per-variant availability
Track stock down to each variant, not just 'the product is available' at the page level.
Availability history
See how often an item sells out and restocks over time to gauge a competitor's demand and supply.
Why timing matters
A competitor selling out of a popular product is a real opportunity - but only if you find out quickly. On paid plans Shop Sentry checks hourly and delivers alerts to email or Telegram within seconds of detection.
Because availability is tracked per variant, you'll know exactly which sizes or colors sold out - often more useful than a blanket 'out of stock' on the product page.
Add a competitor by domain and Shop Sentry discovers and monitors every variant automatically. You only hear from it when availability actually changes.
How it works, with an example
Say a rival sells a popular hoodie in five sizes. Shop Sentry checks each size's availability on schedule. When the Large sells out, you get an alert like 'Out of stock - Classic Hoodie (Large) at rival.com.' When it comes back, you get 'Back in stock - Classic Hoodie (Large).' You see exactly which variant moved and when.
That per-variant detail is the whole point: knowing the Large sold out while other sizes are fine tells you which specific demand you can capture - far more useful than a vague 'this product is low.'
Questions, answered.
Is this for emailing my own customers when my product is back in stock?
No - this tracks your COMPETITORS' stock and alerts YOU when a rival sells out or restocks. If you want to notify your own customers that your product is back, that's a back-in-stock app, which is a different tool.
How fast are restock alerts?
Pro and Agency plans check every hour and deliver alerts within seconds of detecting a change, so you can act while a competitor is still out of stock or right as they restock.
Does it track availability per size and color?
Yes. Availability is tracked at the variant level, so you know exactly which sizes or colors sold out or came back, not just whether the product page says 'in stock'.
Can I get restock alerts in Telegram?
Yes, on paid plans. You can route stock alerts to Telegram, email, or both.
What counts as a restock?
Any variant that moves from unavailable back to available. Sell-outs (available to unavailable) are tracked the same way, so you see both sides of the movement.
Do I need the competitor's cooperation?
No. Shop Sentry reads only public storefront data, so you can monitor any public Shopify store's stock by pasting its domain.