---
title: Cron Triggers
description: Enable your Worker to be executed on a schedule.
image: https://developers.cloudflare.com/dev-products-preview.png
---

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# Cron Triggers

## Background

Cron Triggers allow users to map a cron expression to a Worker using a [scheduled() handler](https://developers.cloudflare.com/workers/runtime-apis/handlers/scheduled/) that enables Workers to be executed on a schedule.

Cron Triggers are ideal for running periodic jobs, such as for maintenance or calling third-party APIs to collect up-to-date data. Workers scheduled by Cron Triggers will run on underutilized machines to make the best use of Cloudflare's capacity and route traffic efficiently.

Note

Cron Triggers can also be combined with [Workflows](https://developers.cloudflare.com/workflows/) to trigger multi-step, long-running tasks. You can [bind to a Workflow](https://developers.cloudflare.com/workflows/build/workers-api/) directly from your Cron Trigger to execute a Workflow on a schedule.

Cron Triggers execute on UTC time.

## Add a Cron Trigger

### 1\. Define a scheduled event listener

To respond to a Cron Trigger, you must add a ["scheduled" handler](https://developers.cloudflare.com/workers/runtime-apis/handlers/scheduled/) to your Worker.

* [  JavaScript ](#tab-panel-9069)
* [  TypeScript ](#tab-panel-9070)
* [  Python ](#tab-panel-9071)

JavaScript

```

export default {

  async scheduled(controller, env, ctx) {

    console.log("cron processed");

  },

};


```

TypeScript

```

interface Env {}

export default {

  async scheduled(

    controller: ScheduledController,

    env: Env,

    ctx: ExecutionContext,

  ) {

    console.log("cron processed");

  },

};


```

Python

```

from workers import WorkerEntrypoint, Response


class Default(WorkerEntrypoint):

    async def scheduled(self, controller, env, ctx):

        print("cron processed")


```

Refer to the following additional examples to write your code:

* [Setting Cron Triggers](https://developers.cloudflare.com/workers/examples/cron-trigger/)
* [Multiple Cron Triggers](https://developers.cloudflare.com/workers/examples/multiple-cron-triggers/)

### 2\. Update configuration

Cron Trigger changes take time to propagate.

Changes such as adding a new Cron Trigger, updating an old Cron Trigger, or deleting a Cron Trigger may take several minutes (up to 15 minutes) to propagate to the Cloudflare global network.

After you have updated your Worker code to include a `"scheduled"` event, you must update your Worker project configuration.

#### Via the [Wrangler configuration file](https://developers.cloudflare.com/workers/wrangler/configuration/)

If a Worker is managed with Wrangler, Cron Triggers should be exclusively managed through the [Wrangler configuration file](https://developers.cloudflare.com/workers/wrangler/configuration/).

Refer to the example below for a Cron Triggers configuration:

* [  wrangler.jsonc ](#tab-panel-9074)
* [  wrangler.toml ](#tab-panel-9075)

JSONC

```

{

  "triggers": {

    // Schedule cron triggers:

    // - At every 3rd minute

    // - At 15:00 (UTC) on first day of the month

    // - At 23:59 (UTC) on the last weekday of the month

    "crons": [

      "*/3 * * * *",

      "0 15 1 * *",

      "59 23 LW * *"

    ]

  }

}


```

TOML

```

[triggers]

crons = [ "*/3 * * * *", "0 15 1 * *", "59 23 LW * *" ]


```

You also can set a different Cron Trigger for each [environment](https://developers.cloudflare.com/workers/wrangler/environments/) in your [Wrangler configuration file](https://developers.cloudflare.com/workers/wrangler/configuration/). You need to put the `triggers` array under your chosen environment. For example:

* [  wrangler.jsonc ](#tab-panel-9076)
* [  wrangler.toml ](#tab-panel-9077)

JSONC

```

{

  "env": {

    "dev": {

      "triggers": {

        "crons": [

          "0 * * * *"

        ]

      }

    }

  }

}


```

TOML

```

[env.dev.triggers]

crons = [ "0 * * * *" ]


```

#### Via the dashboard

To add Cron Triggers in the Cloudflare dashboard:

1. In the Cloudflare dashboard, go to the **Workers & Pages** page.  
[ Go to **Workers & Pages** ](https://dash.cloudflare.com/?to=/:account/workers-and-pages)
2. In **Overview**, select your Worker > **Settings** \> **Triggers** \> **Cron Triggers**.

## Supported cron expressions

Cloudflare supports cron expressions with five fields, along with most [Quartz scheduler ↗](http://www.quartz-scheduler.org/documentation/quartz-2.3.0/tutorials/crontrigger.html#introduction)\-like cron syntax extensions:

| Field         | Values                                                             | Characters   |
| ------------- | ------------------------------------------------------------------ | ------------ |
| Minute        | 0-59                                                               | \* , - /     |
| Hours         | 0-23                                                               | \* , - /     |
| Days of Month | 1-31                                                               | \* , - / L W |
| Months        | 1-12, case-insensitive 3-letter abbreviations ("JAN", "aug", etc.) | \* , - /     |
| Weekdays      | 1-7, case-insensitive 3-letter abbreviations ("MON", "fri", etc.)  | \* , - / L # |

Note

Days of the week go from 1 = Sunday to 7 = Saturday, which is different on some other cron systems (where 0 = Sunday and 6 = Saturday). To avoid ambiguity you may prefer to use the three-letter abbreviations (e.g. `SUN` rather than 1).

### Examples

Some common time intervals that may be useful for setting up your Cron Trigger:

* `* * * * *`  
   * At every minute
* `*/30 * * * *`  
   * At every 30th minute
* `45 * * * *`  
   * On the 45th minute of every hour
* `0 17 * * sun` or `0 17 * * 1`  
   * 17:00 (UTC) on Sunday
* `10 7 * * mon-fri` or `10 7 * * 2-6`  
   * 07:10 (UTC) on weekdays
* `0 15 1 * *`  
   * 15:00 (UTC) on first day of the month
* `0 18 * * 6L` or `0 18 * * friL`  
   * 18:00 (UTC) on the last Friday of the month
* `59 23 LW * *`  
   * 23:59 (UTC) on the last weekday of the month

## Test Cron Triggers locally

Test Cron Triggers using Wrangler with [wrangler dev](https://developers.cloudflare.com/workers/wrangler/commands/general/#dev), or using the [Cloudflare Vite plugin ↗](https://developers.cloudflare.com/workers/vite-plugin/). This will expose a `/cdn-cgi/handler/scheduled` route which can be used to test using a HTTP request.

Terminal window

```

curl "http://localhost:8787/cdn-cgi/handler/scheduled"


```

To simulate different cron patterns, a `cron` query parameter can be passed in.

Terminal window

```

curl "http://localhost:8787/cdn-cgi/handler/scheduled?cron=*+*+*+*+*"


```

Optionally, you can also pass a `time` query parameter to override `controller.scheduledTime` in your scheduled event listener.

Terminal window

```

curl "http://localhost:8787/cdn-cgi/handler/scheduled?cron=*+*+*+*+*&time=1745856238"


```

## View past events

To view the execution history of Cron Triggers, view **Cron Events**:

1. In the Cloudflare dashboard, go to the **Workers & Pages** page.  
[ Go to **Workers & Pages** ](https://dash.cloudflare.com/?to=/:account/workers-and-pages)
2. In **Overview**, select your **Worker**.
3. Select **Settings**.
4. Under **Trigger Events**, select **View events**.

Cron Events stores the 100 most recent invocations of the Cron scheduled event. [Workers Logs](https://developers.cloudflare.com/workers/observability/logs/workers-logs) also records invocation logs for the Cron Trigger with a longer retention period and a filter & query interface. If you are interested in an API to access Cron Events, use Cloudflare's [GraphQL Analytics API](https://developers.cloudflare.com/analytics/graphql-api).

Note

It can take up to 30 minutes before events are displayed in **Past Cron Events** when creating a new Worker or changing a Worker's name.

Refer to [Metrics and Analytics](https://developers.cloudflare.com/workers/observability/metrics-and-analytics/) for more information.

## Remove a Cron Trigger

### Via the dashboard

To delete a Cron Trigger on a deployed Worker via the dashboard:

1. In the Cloudflare dashboard, go to the **Workers & Pages** page.  
[ Go to **Workers & Pages** ](https://dash.cloudflare.com/?to=/:account/workers-and-pages)
2. Select your Worker.
3. Go to **Triggers** \> select the three dot icon next to the Cron Trigger you want to remove > **Delete**.

#### Via the [Wrangler configuration file](https://developers.cloudflare.com/workers/wrangler/configuration/)

If a Worker is managed with Wrangler, Cron Triggers should be exclusively managed through the [Wrangler configuration file](https://developers.cloudflare.com/workers/wrangler/configuration/).

When deploying a Worker with Wrangler any previous Cron Triggers are replaced with those specified in the `triggers` array.

* If the `crons` property is an empty array then all the Cron Triggers are removed.
* If the `triggers` or `crons` property are `undefined` then the currently deploy Cron Triggers are left in-place.

* [  wrangler.jsonc ](#tab-panel-9072)
* [  wrangler.toml ](#tab-panel-9073)

JSONC

```

{

  "triggers": {

    // Remove all cron triggers:

    "crons": []

  }

}


```

TOML

```

[triggers]

crons = [ ]


```

## Limits

Refer to [Limits](https://developers.cloudflare.com/workers/platform/limits/) to track the maximum number of Cron Triggers per Worker.

## Green Compute

With Green Compute enabled, your Cron Triggers will only run on Cloudflare points of presence that are located in data centers that are powered purely by renewable energy. Organizations may claim that they are powered by 100 percent renewable energy if they have procured sufficient renewable energy to account for their overall energy use.

Renewable energy can be purchased in a number of ways, including through on-site generation (wind turbines, solar panels), directly from renewable energy producers through contractual agreements called Power Purchase Agreements (PPA), or in the form of Renewable Energy Credits (REC, IRECs, GoOs) from an energy credit market.

Green Compute can be configured at the account level:

1. In the Cloudflare dashboard, go to the **Workers & Pages** page.  
[ Go to **Workers & Pages** ](https://dash.cloudflare.com/?to=/:account/workers-and-pages)
2. In the **Account details** section, find **Compute Setting**.
3. Select **Change**.
4. Select **Green Compute**.
5. Select **Confirm**.

## Related resources

* [Triggers](https://developers.cloudflare.com/workers/wrangler/configuration/#triggers) \- Review Wrangler configuration file syntax for Cron Triggers.
* Learn how to access Cron Triggers in [ES modules syntax](https://developers.cloudflare.com/workers/reference/migrate-to-module-workers/) for an optimized experience.

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