Seoapp.net as well as other online domains evaluation systems is based on parameters that are available on various sites like Google, Alexa and so on ...
It is often thought that having a domain with short name or with one word is crucial to determine the value of the site, obviously a domain with a single word is much easier to remember, and there are keywords more important than other, meaning they are much sought after on the search engines. In any case if it has a short or long domain or with 1 or more keywords what really makes the difference and therefore increases the value is the content of the site and the level of indexing in search engines, meaning that if the site or pages of the site appear at least in the first 3 pages of google or other search engines , it will be much easier that someone visit your site than of it appear on page 20.
This of course does not depend on us but by the search engine, what we can do is build a site that is of interest and update it continuously.
But let's get to the evaluation of a site. Our system will calculate the alleged traffic generated by the site and accordingly through our algorithm we calculate the value of the site and the value of a link text on homepage considering a max of 8 text link.
I remind you that no online tool you can give the certainty of value but will certainly give you a general idea is if you buy that sell a domain/website