How Zap triggers work

A trigger is an event within an app that starts a Zap. Once you’ve turned your Zap on, Zapier will wait for that trigger event. There are two types of triggers in Zapier: polling or instant.

Trigger types

Each app on Zapier has its own API that allows other apps, like Zapier, to view and edit the app’s data. Zapier triggers use those APIs to get new data (trigger events) to make the Zap run. The type of trigger is defined by each app’s API. Some apps support polling triggers, others support instant triggers, and some support either, depending on the trigger. The trigger type is fixed - you cannot change it.

Polling triggers

With polling triggers, Zapier periodically asks your app for data. This is called polling for new data. Your app responds by sending Zapier its latest data.

Zapier then uses a process called deduplication to check if any of that data is new or updated. The Zap will check if there's new data by comparing each piece of data’s unique ID to IDs the Zap has received before. If the Zap sees a new ID, the Zap runs. If not, the Zap waits for a set period, then asks again, repeatedly polling as long as the Zap is turned on. With polling and deduplication, your Zap will capture new items created since the last poll.

The majority of triggers are polling triggers. They poll the app for data at regular intervals. The interval depends on your Zapier plan.

The shorter the interval, the more often the Zap will poll for new data. If you're on a Pro, Team, or Enterprise plan, you can change how often your polling triggers poll for new data. You can also manually poll for new data in the Zap editor.

Instant triggers

With instant triggers, apps automatically send new data as each trigger event occurs, using webhooks. Webhooks are automated notifications sent between apps. Whenever there is new data, the app will send a webhook to Zapier as soon as that data is created in the app.

In Zapier, instant triggers wait for the app to send new data automatically. Zapier does not have to ask the API if there’s new data. When it receives new data, the Zap runs. Zaps with instant triggers display a lightning bolt icon in the Zap editor.

Testing triggers to return test records

When you test a trigger while creating or editing a Zap, Zapier will attempt to find a recent trigger event from your app that you can use as a test record to build your Zap.

When you test a polling trigger, Zapier will:

• Poll the app for data.
• Display the three most recent trigger items found in the poll.

When you test an instant trigger, Zapier will:

• Retrieve the three most recent items from the connected account.

Limitations

• You cannot change a trigger's type.
• The trigger type is defined by the app’s API.
• You can contact Zapier support to request a new trigger if the one you need does not exist.
• Zaps will only trigger for new data (or updated data if your trigger supports them).
• They will not trigger for old data, including data that was created in your app before the Zap was turned on.
• If you need to transfer existing data, use Zapier’s Transfer feature.
• If your Zap writes data back to the same app and resource that your trigger monitors, the update can retrigger the Zap, creating an infinite loop that rapidly consumes tasks. Common examples include updating a Google Sheets row that triggers on new or updated rows, or building auto-reply workflows that send messages back to the same channel or thread the Zap monitors. Learn more about preventing and fixing Zap loops.
• If a trigger returns a large number of results at once (for example, from a bulk spreadsheet import or CRM migration), Zapier’s flood protection may hold your runs for review instead of processing them immediately. Learn how to adjust flood protection limits.

Learn more about how to set up a Zap trigger.