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Vitamin D Explorer

Live product: a solar vitamin D calculator PWA in six languages. Computes synthesis windows from solar geometry, live UV and skin type — and exposes the same engine to agents over MCP.

The Problem

Public advice about sun exposure is a single number applied to everyone. It ignores latitude, season, altitude, skin type, age and how much skin is uncovered — the variables that actually decide whether any vitamin D gets made. Below UV index 3, none does, and no amount of time outside changes that.

The Solution

A PWA that computes the answer instead of looking it up: NOAA solar declination and elevation, Madronich clear-sky UV with van Heuklon ozone and an altitude correction, and Holick synthesis with MED by Fitzpatrick skin type and an age factor. Live UV and cloud cover come from Open-Meteo. Built on Next.js and Supabase with accounts, saved cities, sun history, web push and a daily cron — and shipped in six languages.

Tags

Next.jsSupabasePWAD3i18nWeb Push

Outcomes

  • Live at getvitamind.app, open source under MIT
  • Six languages (es/en/fr/de/ru/lt), installable PWA with web push
  • CI quality gate on every push: lint, typecheck, tests and build