Queues

Queues deliver messages from a producer Worker to a consumer Worker. Delivery is at-least-once. Durability comes from scheduler.sqlite on the node running ocd.

For example, you can use Queues for:

• Decoupling producer and consumer Workers
• Buffering work for asynchronous processing
• Retrying failed deliveries

export default {
  async fetch(request: Request, env: Env): Promise<Response> {
    await env.QUEUE.send({ hello: "world" });
    return new Response("queued");
  },
  async queue(batch: MessageBatch<{ hello: string }>, env: Env): Promise<void> {
    for (const message of batch.messages) {
      console.log(message.body);
      message.ack();
    }
  },
} satisfies ExportedHandler<{ QUEUE: Queue }>;

Bind a producer with Wrangler’s standard Queues field:

{
  "name": "queue-app",
  "main": "src/index.ts",
  "queues": {
    "producers": [{ "binding": "QUEUE", "queue": "jobs" }],
    "consumers": [{ "queue": "jobs", "max_batch_size": 10 }]
  }
}

A consumer targets the Worker’s queue handler through queues.consumers. Binding grammar: bindings. Pinned Wrangler owns queue provisioning and consumer configuration.

Compatibility

Topic	Cloudflare	open-compute
JavaScript API	Queues JavaScript APIs	Same: send / sendBatch, contentType (json / text / bytes / v8), delaySeconds, metrics, consumer MessageBatch / ack / retry
Durability	Global replication	Local scheduler.sqlite on the node running ocd
Delivery	At-least-once	At-least-once
Global FIFO	Available	Not provided
Unknown native dispatch	—	May retain the lease; duplicate attempt numbers possible
Pull consumer	Available	Not provided
Binding	Wrangler queues	Standard producers and consumers entries

Next: Develop with bindings · Compatibility and limits