WHY. is a structural email conversion diagnostic for B2B SaaS teams. Paste any email and get a score from 1 to 10, a named failure pattern, and a rebuilt version in 90 seconds, no copy opinions, no generic best practices.Built on the Decision Friction Model, validated across 59 real teardowns averaging 3.4/10 before rebuild and 9/10 after. WHY. catches structural failures like Guest Language CTAs, Feature-First Bias, and Filing Label subjects that generic copy advice never catches.Free tier included. Paid plans add A/B subject lines, content calendars, and full campaign rebuilds.Built by Strategic Flow, the team also behind ToolIndex.