Below, we present some of the most valid tools available on the web that help you optimize SEO, indicating any problems to solve to obtain a better positioning on search engines.
Semrush
Semrush is a complete online marketing tool that allows users to manage their web strategies. You can use it to perform keyword research, analyze your competitors, create landing pages and much more.
The platform offers a wealth of useful tools for any type of online marketing project. Semrush also uses web crawlers for two main reasons:

To build and maintain your backlink database. With the Backlink Audit tool you can check your competitors' backlink profiles.
To analyze the health of your site, through Site Audit : this is a crawler that studies and classifies the contents of websites to allow you to check their health.