> ## Documentation Index
> Fetch the complete documentation index at: https://docs.zopio.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# Cron Jobs

> Create serverless functions that run on specific intervals.

By default, `zopio` uses Vercel's cron jobs feature to trigger Next.js serverless functions on a schedule. However, you can replace this setup with the background job service of your choosing, such as trigger.dev or BetterStack.

## Writing functions

Next.js serverless functions act as the basis for scheduled jobs. You can write them in any runtime and trigger them using a simple HTTP call.

To demonstrate, we've created a example endpoint called `keep-alive` that creates, then subsequently deletes, a temporary `page` object in the database. This is a little workaround to prevent databases going to sleep after a period of inactivity. You should probably remove this if you don't need it.

Additionally, while you can add cron jobs to any app, we use the `api` app to keep our background jobs, webhooks and other such tasks isolated from our UI.

You can add new functions by creating the relevant `route.ts` files in the `apps/api/app/cron` folder. While you can put them anywhere, we use the aptly named `cron` folder to hold our endpoints designed to run as cron jobs. For example:

```ts apps/api/app/cron/[your-function]/route.ts theme={"system"}
import { database } from '@repo/database';

// Must use GET for Vercel cron jobs
export const GET = async () => {
  // Do stuff

  return new Response('OK', { status: 200 });
};
```

## Scheduling functions

After you write your serverless function, you can schedule it by amending the `vercel.json` file in the API app. To serve as an example, we've wired up the `keep-alive` job mentioned above to run every 10 minutes.

```json apps/api/vercel.json theme={"system"}
{
  "crons": [
    {
      "path": "/cron/keep-alive",
      "schedule": "0 1 * * *"
    }
  ]
}
```

## How Vercel triggers cron jobs

To trigger a cron job, Vercel makes an HTTP GET request to your project's production deployment URL, using the path provided in your project's vercel.json file. For example, Vercel might make a request to:

```
https://*.vercel.app/cron/keep-alive
```

## Triggering functions manually

Should you need to trigger a cron job manually, you can either do so in the Vercel dashboard or just hit the endpoint with a standard HTTP request. For example:

```sh Terminal theme={"system"}
curl -X GET http://localhost:3002/cron/keep-alive
```

<Tip>
  For more complex Event-Driven Workflows and Background Jobs, you can use [Trigger.dev](/packages/trigger) and [Trigger Rules](/packages/trigger-rules).
</Tip>