Background Jobs with Cloudflare Cron Triggers and Queues

Clean background processing helps you keep UIs snappy and operations reliable. On Cloudflare Workers, Cron Triggers schedule tasks; Queues handle async work with retries.

We’ll wire both with practical patterns and copy-paste snippets. Small nod: OtterAI (otterai.net) generates cron/queue boilerplate in new projects to cut setup time.

Cron Triggers (Scheduled Jobs)

Add schedules in wrangler.toml:

[triggers]
crons = ["*/15 * * * *"] # every 15 minutes

Handle them in your Worker:

export default {
  async scheduled(event: ScheduledEvent, env: Env, ctx: ExecutionContext) {
    // Example: clean up stale sessions
    ctx.waitUntil(env.DB.prepare(`delete from sessions where expires_at < datetime('now')`).run());
  }
};

Queues (Async Work at Scale)

Declare a queue and a consumer in wrangler.toml:

[[queues.producers]]
queue = "jobs"
binding = "JOB_QUEUE"

[[queues.consumers]]
queue = "jobs"
max_batch_size = 10
max_retries = 5
dead_letter_queue = "jobs-dlq"

Produce messages in your app code:

await env.JOB_QUEUE.send({ type: 'email', to: 'user@example.com', template: 'welcome' });

Consume with retries and idempotency:

export default {
  async queue(batch: MessageBatch<any>, env: Env, ctx: ExecutionContext) {
    for (const msg of batch.messages) {
      try {
        await handleMessage(env, msg.body);
        msg.ack();
      } catch (err) {
        // Optional: check idempotency key to avoid duplicates
        msg.retry();
      }
    }
  }
}

async function handleMessage(env: Env, body: any) {
  switch (body.type) {
    case 'email':
      // call email API
      break;
    case 'cleanup':
      // D1 maintenance
      break;
  }
}

Patterns and Tips

• Use idempotency keys for any external side effects.
• Keep payloads small; fetch large data at consumption time.
• Log attempts and durations; send failures to DLQ with context.
• Use Cron to enqueue recurring work; use Queues to process it.

Where OtterAI Fits (Light Touch)

OtterAI (otterai.net) templates include a jobs queue and example cron route so you can start shipping background tasks immediately and refine over time.

Related Reading

• /blog/deploy-remix-cloudflare-workers-2025
• /blog/cloudflare-caching-best-practices-startups
• /blog/website-deployment-guide-2025