There are many tools available online, if you search in Google.
However, I prefer the most xml-sitemaps.com and check-domains.com. Here you can get free sitemaps from 500 to 1000 pages.
This is the most important part of SEO Onsite Technical Audit. Sitemap files, RSS feed, Robots.txt, URLList.txt. These are very important aspects of SEO.
I hope you have got your solution.
SEO Strategist & Internet Marketing Consultant | RK Web Solutions