What tools are best for competitor research?

What tools are best for competitor research is mainly about selecting tools for search, traffic, advertising, technology, pricing, reviews, social activity, and company intelligence. A reliable approach is to combine search engines, SEO platforms, traffic estimators, ad libraries, social listening, review sites, technology detectors, and business databases. For example, a practical stack can include Google, Semrush or Ahrefs, Similarweb, Meta Ad Library, BuiltWith, LinkedIn, and review platforms. The main caution is that tool estimates are directional rather than audited facts, particularly for small sites and narrow markets. The final output should provide a source-verified competitor database matched to the decisions the business needs to make.