Temperat.io

THE PROBLEM

Existing tuners ship one temperament — Equal — and force users into native iOS/Android installs with paywalls. Anyone working with historical instruments, microtonal music, or alternative reference pitches (415, 432, 442 Hz) has to fight the tool. There was room for a browser-based tuner that handled real temperament work, ran on any device, cost nothing, and tracked nothing.

THE APPROACH

• Slim runtime by design: Next.js + React + pitchy for client-side pitch detection. No server, no auth, no analytics, no cookies, no third-party scripts — the entire app runs locally in the browser via Web Audio.
• 21 historical tuning systems built in: 12-TET, Just Intonation, Pythagorean, meantone variants, Werckmeister III, Kirnberger III, Vallotti, Young, Bach/Lehman, Neidhardt, Kellner, and more — grouped by era so users can browse the lineage.
• Adjustable reference pitch (A = 415 / 432 / 440 / 442 / 444 Hz) plus an optional Railsback-curve toggle for piano inharmonicity.
• Installable PWA with strict CSP (self-only) and a stamped service worker for offline use. /donate page wires four Stripe Payment Links so support is one tap.
• Open-sourced under MIT on GitHub. Test stack: Vitest unit tests + Playwright E2E. Holistic audit cleared LOW + NIT + MEDIUM + HIGH tiers in successive PRs.