NeetoSEO is a downloadable desktop app, not a web application. It is built using Electron, which is based on the Chromium browser.
If NeetoSEO is a web-based application, then that would incur a lot of cost. There is a cost involved in crawling the sites and collecting the pages. Then there is a cost involved in analyzing each page to check the page title, meta tag size, image size, OG tags and whatnot.
This means that after collecting and analyzing a few pages, NeetoSEO will ask you to sign up for a paid plan.
We decided to use a downloaded app. This way, your laptop's computing power is used to crawl the sites and analyze the pages. Also, you pay for the bandwidth cost incurred when downloading the pages and images.
In this way, you can do site audits of an unlimited number of sites with unlimited pages.