SimilarWeb gives you a rough picture of how much traffic a website gets, where that traffic comes from, and what other sites are in the same space. You can enter any domain and see estimated visits, top countries, referral sources, and engagement metrics like pages per visit and average time on site. For public companies, it also shows stock information and financials. It's not exact — no external tool can see a site's internal analytics — but it's useful for comparing sites and understanding a market.

The free version provides a limited view, while paid plans unlock more detailed data, keyword analysis, and lead generation tools. Marketers use it for competitor research, investors use it to evaluate digital businesses, and website owners use it to benchmark their performance. If you've ever wondered how your site compares to others in your niche, it's one of the more accessible tools for that.