local url = "https://example.org/update.php"

local function sendUsers()
    local users = {}
    for steamid, data in pairs( ULib.ucl.users ) do
        users[ util.SteamIDTo64( steamid ) ] = data.group
    end
    http.Post(url, { data=util.TableToJSON( users ) })
end

local hooks = {
    ULib.HOOK_GROUP_RENAMED,
    ULib.HOOK_USER_GROUP_CHANGE,
    ULib.HOOK_USER_REMOVED
}
for i=1, #hooks do
    hook.Add( hooks[i], "loadingscreen", sendUsers )
end