Google Trends

Google Trends shows relative search interest for a term over time and by region, drawn from actual Google search volume.

It is free and it answers a question no paid tool answers better: is demand for this growing, flat or declining, and where is it concentrated — which is worth checking before committing to a niche.

Values are relative rather than absolute: 100 means the peak within the period selected, not a number of searches, so comparisons only hold within a single query.