Where the free Google tools can provide complementary value is in fact-checking. If you're checking out more than one of these SEO tools, you'll quickly realize this isn't an exact science. If you were to look at the PA, DA, and keyword difficulty scores across KWFinder.com, Moz, SpyFu, SEMrush, Ahrefs, AWR Cloud, and Searchmetrics for the same set of keywords, you might get different numbers across each metric separated by anywhere from a few points to dozens. If your business is unsure about an optimization campaign on a particular keyword, you can cross-check with data straight from a free AdWords account and Search Console. Another trick: Enable Incognito mode in your browser along with an extension like the free Moz Toolbar and you can run case-by-case searches on specific keywords to get an organic look at your target search results page.
Robots.txt is not an appropriate or effective way of blocking sensitive or confidential material. It only instructs well-behaved crawlers that the pages are not for them, but it does not prevent your server from delivering those pages to a browser that requests them. One reason is that search engines could still reference the URLs you block (showing just the URL, no title or snippet) if there happen to be links to those URLs somewhere on the Internet (like referrer logs). Also, non-compliant or rogue search engines that don't acknowledge the Robots Exclusion Standard could disobey the instructions of your robots.txt. Finally, a curious user could examine the directories or subdirectories in your robots.txt file and guess the URL of the content that you don't want seen.
Other research shows that exact-match domains that are deemed to be relevant, valuable, and high-quality can see a ranking boost because of it. However, if you already have an established website, you don’t need to go looking for an exact-match domain for your business; focus on a URL that reflects your business and optimize the heck out of it instead!