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Transform Rules

Transform Rules allow you to adjust the URI path, query string, and HTTP headers of requests and responses on the Cloudflare global network.

There are several types of Transform Rules:

To configure Transform Rules in the dashboard, go to the Transform Rules page in Rules.

For more complex header modifications and rewrite logic, consider using Snippets.


Get started

Cloudflare provides you with rules templates for common use cases. In the dashboard, go to your zone > Rules > Templates and select one of the available templates. You can also refer to the Examples gallery in the developer docs.

Alternatively, create a transform rule from scratch in the dashboard or via Cloudflare API. Refer to the following sections for detailed instructions:

Refer to Rules language for more information on building expressions for Transform Rules.

Availability

Cloudflare Transform Rules are available to all customers. Support for regular expressions depends on your Cloudflare plan.

This table outlines the Transform Rules features available with each customer plan:

Free Pro Business Enterprise

Availability

Yes

Yes

Yes

Yes

Active Transform Rules

10 25 50 100

Regex support

No

No

Yes

Yes

A Cloudflare user must have the Firewall role or one of the Administrator roles to access Transform Rules.

Transform Rules evaluation

Managed Transforms run before other types of Transform Rules that modify HTTP headers:

  • Managed Transforms that adjust HTTP request headers run before HTTP request header modification rules.
  • Managed Transforms that adjust HTTP response headers run before HTTP response header modification rules.

Transform Rules run in order. Rules that appear later in the list of Transform Rules can overwrite changes done by previous rules. You can define the rule order in the dashboard or via API.

Request and response fields are immutable within each phase while evaluating Transform Rules for a request/response. For more information, refer to Rule evaluation and field values.

Troubleshooting

When troubleshooting Transform Rules, use Cloudflare Trace to determine if a rule is triggering for a specific URL.