Free sitemap generator for large website

Hi, I have an old website which contains about 6000 pages. I need to build sitemap for this site. Is there any free tool nowadays which can build the sitemap? I don't want to buy any commercial tool because I need to build that sitemap only at once. It's not Wordpress website. Thank you.

The only free generator with the highest number of generated pages (4300) I found is this > http://www.web-site-map.com/xml-sitemaps.php

Depending on their server load, the limit increases, so possibly check it at different times/days and see how high the limit goes.

Also there's this one, which seems to be 50k pages, but looks a bit complicated, not sure if you'll understand how to install it > https://www.npmjs.com/package/sitemap-generator

I found this one: http://www.xsitemap.com

Works well, very slow but is doesn't matter...