Scheduled Tasks & Crons

Some tasks need to run on a schedule — checking for updates, generating reports, cleaning up data. Cloudflare Workers Cron Triggers make this serverless and free.

Cron Triggers on Cloudflare Workers

A Worker can be triggered on a schedule instead of (or in addition to) HTTP requests:

wrangler.toml

[triggers]
crons = ["0 * * * *"]  # Every hour

export default {
  // HTTP handler (optional)
  async fetch(request: Request, env: Env) {
    return new Response('OK');
  },

  // Cron handler
  async scheduled(event: ScheduledEvent, env: Env, ctx: ExecutionContext) {
    // This runs on schedule
    await checkForUpdates(env);
  },
};

Common Scheduled Tasks

Daily Site Health Check

> Create a Worker cron that runs daily and:
> 1. Checks that our main site returns 200
> 2. Checks response time
> 3. Stores the result in D1
> 4. Sends a Slack notification if anything is wrong

Weekly Content Report

> Create a cron Worker that every Monday:
> 1. Queries D1 for content published last week
> 2. Generates engagement statistics
> 3. Creates a summary report
> 4. Stores it in R2

Data Cleanup

> Create a cron that runs nightly and:
> 1. Deletes expired sessions from KV
> 2. Removes orphaned files from R2
> 3. Archives old records in D1

Cron Schedule Syntax

┌─── minute (0-59)
│ ┌─── hour (0-23)
│ │ ┌─── day of month (1-31)
│ │ │ ┌─── month (1-12)
│ │ │ │ ┌─── day of week (0-6, Sun=0)
│ │ │ │ │
* * * * *

Common patterns:

• */5 * * * * — every 5 minutes
• 0 * * * * — every hour
• 0 0 * * * — daily at midnight
• 0 0 * * 1 — every Monday
• 0 0 1 * * — first of every month

Building with Claude

Ask Claude to create the complete cron Worker:

> Create a Cloudflare Worker with a cron trigger that runs every 6 hours.
> It should:
> 1. Fetch our WordPress site's latest posts via REST API
> 2. Compare with what's stored in D1
> 3. If there are new posts, store them in D1
> 4. Log a summary of new posts found
>
> Include the wrangler.toml configuration.

Claude will create the Worker code, types, and Wrangler config — ready to deploy.

Exercise

1. Think of a recurring task in your workflow
2. Ask Claude to build a cron Worker for it
3. Test locally with wrangler dev
4. Deploy and monitor with wrangler tail