However, things are a bit more complex when it comes to paid tools. An agency that offers professional SEO services might use Ahrefs, SEMrush, or Moz Pro. Although programs like SPyFu are also worth considering. What is the advantage of these applications? For one, they can allow you to perform a link analysis of your pages or those of your rivals, deploy the necessary resources for the SEO audit process, analyze keywords relevant to your field of activity, or create an XML sitemap to help search engine algorithms analyze your content.