Requestly's Modify API Response rule lets you directly modify the response of top-level HTML documents. This feature is only available for desktop app but you can use file server and redirect rule as a workaround for most use cases.
Click here to download the Desktop App for your OS.
Create a Response Rule
Navigate to the HTTP Rules section in the Requestly app. Click + New Rule and choose the Modify API Response option.
Name and Describe Your Rule
Provide a descriptive name for the rule to keep your setup organized. Optionally, add a brief description explaining its purpose for easier identification later.
Select Resource Type
In the Resource Type choose HTML/ JS/ CSS
Define Matching Criteria
Define the criteria for the rule to be applied, such as URL, Host, or Path. Choose from Regex, Contains, Wildcard, or Equals, or use Advance Filters for more precise conditions.
For more detailed guidance, refer to the Source Conditions Guide.
Change Response Status Code
Modify the status code of the response using the dropdown menu. Choose from:
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2XXfor successful responses -
4XXfor client errors -
5XXfor server errors
If left empty, the original status code remains unchanged.
Modify Response Data
Choose one of the following methods to modify the response data:
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Static Response Modification: Input a static value as the response body.
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Dynamic Modification Script (JavaScript): Use JavaScript to modify responses dynamically. The script provides access to parameters like:
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method: HTTP Method (GET, POST, etc.) -
url: Full URL of the request -
response: Original response body (string) -
responseType: Content type of the original response -
requestHeaders: Headers sent with the request -
responseJSON: Original response parsed as a JSON object
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Save and Activate the Rule
Click Save to store the rule and toggle it ON. This will apply the rule to the defined source conditions.