Google Analytics 4

Google Analytics 4 (GA4) is the free, next-generation analytics platform from Google. While not exclusively an SEO tool, it's critical for measuring SEO success by tracking organic traffic, user engagement, conversions, and behavior flow. Its event-based model and AI-powered insights help startups understand how users from search interact with their site. Integration with Search Console provides direct query and landing page performance data.

It's a must-have for any data-driven startup. It's free and scores highly for its deep integration with the Google ecosystem, powerful exploration reports, and its role in connecting SEO efforts to business outcomes.