import libcurl

proc curlWriteFn(
    buffer: cstring,
    size: int,
    count: int,
    outstream: pointer): int =

    let outbuf = cast[ref string](outstream)
    outbuf[] &= cast[string](buffer)[0..count]
    result = size*count

let webData: ref string = new string
let curl = easy_init()

discard curl.easy_setopt(OPT_USERAGENT,"Mozilla/5.0")
discard curl.easy_setopt(OPT_FOLLOWLOCATION,true)
discard curl.easy_setopt(OPT_MAXREDIRS,5)
discard curl.easy_setopt(OPT_WRITEDATA,webData)
discard curl.easy_setopt(OPT_WRITEFUNCTION,curlWriteFn)
discard curl.easy_setopt(OPT_url,"path/to/zipfile.zip")

let ret = curl.easy_perform()
if ret==E_OK:
    echo "download completed"
let wf = open("zipfile.zip", fmWrite)
wf.write(webData[])
wfile.close()