Hello people, i just joined. thought i would add my 2 cents.
Why use someone else's platform, give them your information about your site (hey, i know its freely available information as its on the internet, but still!).
Making a site map is really easy, you can do it in most languages, its just a matter of getting all the paths of all the pages in your site you want the world to know about, along with any other specifics about the pages/site, and build up an xml file.
It depends what you want it for, google sitemap, or whatever else be it internal or external to your website/app, that the structure matters.
PHP is the easiest - you can quite easily write a loop to go through all the pages in each directory of the website and build it all into an xml file with titles and categories or whatever - if say, for google shopping.
I have done sitemaps previously a few times, and beyond a bit of dicking around to get the xml markup, attributes and encoding, its easy to do and is always uptodate as you you can have it fire on page load or whatever.
I can give you code if you want, or give you a better highlevel of how to do it.
But giving it to some website to do it, just sounds meh.