Use the [Rulesets API](https://developers.cloudflare.com/ruleset-engine/rulesets-api/) to create a custom rule via API.

You must deploy custom rules to the `http_request_firewall_custom` [phase entry point ruleset](https://developers.cloudflare.com/ruleset-engine/about/rulesets/#entry-point-ruleset).

## Create a custom rule

To create a custom rule for a zone, add a rule to the `http_request_firewall_custom` phase entry point ruleset.

1. Invoke the [Get a zone entry point ruleset](https://developers.cloudflare.com/api/resources/rulesets/subresources/phases/methods/get/) operation to obtain the definition of the entry point ruleset for the `http_request_firewall_custom` phase. You will need the [zone ID](https://developers.cloudflare.com/fundamentals/setup/find-account-and-zone-ids/) for this task.

2. If the entry point ruleset already exists (that is, if you received a `200 OK` status code and the ruleset definition), take note of the ruleset ID in the response. Then, invoke the [Create a zone ruleset rule](https://developers.cloudflare.com/api/resources/rulesets/subresources/rules/methods/create/) operation to add a custom rule to the existing ruleset. Refer to the examples below for details.

3. If the entry point ruleset does not exist (that is, if you received a `404 Not Found` status code in step 1), create it using the [Create a zone ruleset](https://developers.cloudflare.com/api/resources/rulesets/methods/create/) operation. Include your custom rule in the `rules` array. Refer to [Create ruleset](https://developers.cloudflare.com/ruleset-engine/rulesets-api/create/#example---create-a-zone-level-phase-entry-point-ruleset) for an example.

### Example A

This example request adds a rule to the `http_request_firewall_custom` phase entry point ruleset for the zone with ID `{zone_id}`. The entry point ruleset already exists, with ID `{ruleset_id}`.

The new rule, which will be the last rule in the ruleset, will challenge requests from the United Kingdom or France with an attack score lower than `20`:

```bash
curl https://api.cloudflare.com/client/v4/zones/{zone_id}/rulesets/{ruleset_id}/rules \
--header "Authorization: Bearer <API_TOKEN>" \
--header "Content-Type: application/json" \
--data '{
  "description": "My custom rule",
  "expression": "(ip.src.country eq \"GB\" or ip.src.country eq \"FR\") and cf.waf.score lt 20",
  "action": "challenge"
}'
```

To define a specific position for the new rule, include a `position` object in the request body according to the guidelines in [Change the order of a rule in a ruleset](https://developers.cloudflare.com/ruleset-engine/rulesets-api/update-rule/#change-the-order-of-a-rule-in-a-ruleset).

For instructions on creating an entry point ruleset and defining its rules using a single API call, refer to [Add rules to phase entry point rulesets](https://developers.cloudflare.com/ruleset-engine/basic-operations/add-rule-phase-rulesets/).

### Example B

This example request adds a rule to the `http_request_firewall_custom` phase entry point ruleset for the zone with ID `{zone_id}`. The entry point ruleset already exists, with ID `{ruleset_id}`.

The new rule, which will be the last rule in the ruleset, includes the definition of a [custom response](https://developers.cloudflare.com/waf/custom-rules/create-dashboard/#configure-a-custom-response-for-blocked-requests) for blocked requests:

```bash
curl https://api.cloudflare.com/client/v4/zones/{zone_id}/rulesets/{ruleset_id}/rules \
--header "Authorization: Bearer <API_TOKEN>" \
--header "Content-Type: application/json" \
--data '{
  "description": "My custom rule with plain text response",
  "expression": "(ip.src.country eq \"GB\" or ip.src.country eq \"FR\") and cf.waf.score lt 20",
  "action": "block",
  "action_parameters": {
    "response": {
      "status_code": 403,
      "content": "Your request was blocked.",
      "content_type": "text/plain"
    }
  }
}'
```

To define a specific position for the new rule, include a `position` object in the request body according to the guidelines in [Change the order of a rule in a ruleset](https://developers.cloudflare.com/ruleset-engine/rulesets-api/update-rule/#change-the-order-of-a-rule-in-a-ruleset).

For instructions on creating an entry point ruleset and defining its rules using a single API call, refer to [Add rules to phase entry point rulesets](https://developers.cloudflare.com/ruleset-engine/basic-operations/add-rule-phase-rulesets/).

***

## Next steps

Use the different operations in the [Rulesets API](https://developers.cloudflare.com/ruleset-engine/rulesets-api/) to work with the rule you just created. The following table has a list of common tasks:

| Task                      | Procedure                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |
| ------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| List all rules in ruleset | Use the [Get a zone entry point ruleset](https://developers.cloudflare.com/api/resources/rulesets/subresources/phases/methods/get/) operation with the `http_request_firewall_custom` phase name to obtain the list of configured custom rules and their IDs.For more information, refer to [View a specific ruleset](https://developers.cloudflare.com/ruleset-engine/rulesets-api/view/#view-a-specific-ruleset).                                                                                                                                      |
| Update a rule             | Use the [Update a zone ruleset rule](https://developers.cloudflare.com/api/resources/rulesets/methods/update/) operation.You will need to provide the ruleset ID and the rule ID. To obtain these IDs, you can use the [Get a zone entry point ruleset](https://developers.cloudflare.com/api/resources/rulesets/subresources/phases/methods/get/) operation with the `http_request_firewall_custom` phase name.For more information, refer to [Update a rule in a ruleset](https://developers.cloudflare.com/ruleset-engine/rulesets-api/update-rule/). |
| Delete a rule             | Use the [Delete a zone ruleset rule](https://developers.cloudflare.com/api/resources/rulesets/methods/delete/) operation.You will need to provide the ruleset ID and the rule ID. To obtain these IDs, you can use the [Get a zone entry point ruleset](https://developers.cloudflare.com/api/resources/rulesets/subresources/phases/methods/get/) operation with the `http_request_firewall_custom` phase name.For more information, refer to [Delete a rule in a ruleset](https://developers.cloudflare.com/ruleset-engine/rulesets-api/delete-rule/). |

These operations are covered in the Ruleset Engine documentation. The Ruleset Engine powers different Cloudflare products, including custom rules.
