Hi, it is currently not possible to specify a filename for a binary response. I suggest adding support for this using content disposition information.

The Content-Disposition response header field is used to convey additional information about how to process the response payload, and also can be used to attach additional metadata, such as the filename to use when saving the response payload locally.

See: RFC 6266 - Use of the Content-Disposition Header Field in the Hypertext Transfer Protocol (HTTP)

This can be implemented in the same way as the content type header field.