Employer Cost API calculates the true cost-to-employer for any U.S. worker. It includes employer payroll taxes (Social Security, Medicare, FUTA, SUTA), workers’ comp, employer-paid benefits, retirement match, PTO cost, and full annual and per-period breakdowns. Designed for HR SaaS, payroll tools, finance apps, and startups that need accurate compensation modeling. Simple JSON output, fast responses, and clean developer experience.