Sitemap.ai is a web-based crawler that produces an XML sitemap, llms.txt and per-page markdown from one crawl of your live URL, so it works with any CMS. The homepage says it is free, includes llms.txt and standard XML, and needs no credit card.
Guests get 500 URLs per crawl. A free account gets 5,000 URLs per crawl and 50,000 URLs a month, with JavaScript rendering, saved projects and re-crawls. Scheduled crawls are free with an account, and no paid plans are shown.
Sitemap.ai was built to make complete sitemaps easier to generate and keep up to date from a single crawl.