filibot is the generic name for Fili's SEO crawler.
Your site will probably be requested by filibot when someone is manually using one of Fili's free SEO tools to analyze the SEO signals of your site. For most sites, filibot shouldn't access your site more than once every few seconds on average, and extremely infrequently. However, due to network delays it's possible that the rate will appear to be slightly higher over short periods.
SEO Tools which may be using filibot include, but are not limited to:
filibot identifies itself with:
Mozilla/5.0 (compatible; filibot/1.0; +https://filibot.com/)
If you have any concerns regarding filibot's requests, you can block filibot in your robots.txt file.