CalcStack is an interactive content platform for lead generation. Businesses embed interactive calculators and tools on their websites to convert visitors into qualified leads. Unlike static forms that convert 2-3%, interactive content converts 30-50% of visitors. CalcStack includes 140+ pre-built templates across 14 industries, industry benchmarks, AI-powered tool generation, conditional insights, lead scoring, and integrations with HubSpot, Salesforce, Zapier, and more. Free forever with paid plans from £29/month.