The "test-httpmsg" command:

Usage: fossil test-httpmsg URL ?PAYLOAD? ?OPTIONS?

Send an HTTP message to URL and get the reply. PAYLOAD is a file containing
the payload, or "-" to read payload from standard input.  a POST message
is sent if PAYLOAD is specified and is non-empty.  If PAYLOAD is omitted
or is an empty file, then a GET message is sent.

Options:

    --compress                 Use ZLIB compression on the payload
    --mimetype TYPE            Mimetype of the payload
    --out FILE                 Store the reply in FILE
    -v                         Verbose output