# Webhook

> A webhook is a message Shopify sends to an app the moment something happens in your store, so the app does not have to keep asking.

- Source: https://storestandards.com/glossary/webhook/
- Updated: 2026-08-14
- Author: Priya Raghunathan, Founder, engineer, Store Standards

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An order is placed, and within a second Shopify has told every app that asked
to know.

## Why it matters to a stockroom

The alternative is polling: an app asking "anything new?" every minute,
forever. That is slower, wastes your
[Admin API](https://storestandards.com/glossary/admin-api/) limit, and still misses things between
checks.

With webhooks, a change to an
[inventory item](https://storestandards.com/glossary/inventory-item/) reaches a warehouse system while
the person who made it is still standing at the shelf.

## Expect it twice

Shopify guarantees delivery at least once, not exactly once. A network blip
means the same message arrives again.

Any integration worth trusting handles that, usually by recording the message
id and ignoring one it has already seen. An app that does not will book the
same delivery into your stock twice.

## Where it goes wrong

The receiving end goes down for an hour. Shopify retries for a while and then
gives up, and those messages are gone. A good integration reconciles on a
schedule as well as listening, so a missed hour is caught by the next sweep
rather than never.

The other one is reaching for a webhook when
[Shopify Flow](https://storestandards.com/glossary/shopify-flow/) would do. If the action is an email or
a tag, Flow needs no server and nothing to keep running.

## Related terms

- [Admin API](https://storestandards.com/glossary/admin-api/): The Admin API is how apps read and change things in your Shopify store, including the stock levels a scanner updates.
- [Shopify Flow](https://storestandards.com/glossary/shopify-flow/): Shopify Flow is Shopify's own automation tool. It watches for something happening in your store and runs an action when it does.
- [Inventory item](https://storestandards.com/glossary/inventory-item/): An inventory item is the countable half of a variant. Stock levels attach to it, one per location, not to the variant itself.