Automatic request headers

When using the REST API to fetch content via Browser Rendering, Cloudflare adds the following headers to outbound requests made to the target URL:

Header	Description
cf-biso-request-id	A unique identifier for the Browser Rendering request
cf-biso-devtools	A flag indicating the request originated from Cloudflare's rendering infrastructure

Note

These headers are unique to Browser Rendering and are automatically included and cannot be removed or overridden (such as via setExtraHTTPHeaders). They are intended to ensure transparency, allowing destination servers to identify traffic as coming from Cloudflare Browser Rendering.