---
title: cf.worker.upstream_zone · Cloudflare Ruleset Engine docs
description: Identifies whether a request comes from a worker or not.
chatbotDeprioritize: false
source_url:
  html: https://developers.cloudflare.com/ruleset-engine/rules-language/fields/reference/cf.worker.upstream_zone/
  md: https://developers.cloudflare.com/ruleset-engine/rules-language/fields/reference/cf.worker.upstream_zone/index.md
---

# cf.worker.upstream\_zone

`cf.worker.upstream_zone` String

Identifies whether a request comes from a worker or not.

When a request comes from a worker, this field will hold the name of the zone for that worker. Otherwise, `cf.worker.upstream_zone` is empty.

Categories:

* Request
