Most of the hydration apps tells you to drink 8 glasses. Same number on a 30°C marathon day and a cool desk day. Same target whether you slept 8 hours or 4. Same plan whether you're 60 kg or 90 kg.

Vari is different. It builds your hydration plan around your actual day — your weight, your weather, your workouts, and how you slept last night. The number changes when your day changes. That's the whole point.

— What Vari does —

▸ Adaptive daily goal — Personalised from weight, activity, climate, caffeine intake. Bumps automatically on poor-sleep days (vasopressin biology, not vibes).

▸ Smart Schedule — Time-stamped slots from wake to two hours before bed. Heavier weight at the wake slot, pre-caffeine slots 30 minutes before each coffee, and a 13:00–14:00 boost to pre-empt the afternoon energy dip.

▸ One-tap drink logging — 250 ml in two seconds. No menus, no friction. Quick types for water, coffee, tea, and electrolytes.

▸ Apple Health integration — Reads your workouts and sleep, writes your hydration logs back. Two-way sync that respects HealthKit privacy boundaries.

▸ Day-3 Insights — As soon as Vari has 3 days of data and 1 night of sleep, you get the lag-1 correlation: "yourhydration today predicts how you'll feel tomorrow." This is the killer insight most apps don't surface.

▸ Time-of-day patterns — Vari spots your weak hours (most people miss the 14:00–16:00 dip) and offers one-tap reminders that drop where you actually fall behind.

▸ Weekly Story — Shareable Sunday recap with your hydration consistency, sleep correlation, and a single headline insight. Ships as a vertical card for Stories.

▸ Family Hydration — Web dashboard for households. Track your kids and partner without forcing them onto another app. Their iPhone logs flow in via shared HealthKit; your dashboard sees the household at a glance.

— Why Vari is different —

Most water-tracking apps are calorie-counter-shaped: pick a static target, log everything, hit a streak. Vari treats hydration as an output of your day, not a fixed input. The schedule and goal both move when your inputs move.

Three things make this work:

1. The science is real — Vari's calculators cite IOM (2004), ACSM (sweat-rate), KDOQI (CKD-safe limits), Maughan Griffin (caffeine + hydration), Rosinger et al. (Sleep, 2019, sleep-debt → hydration deficit), and Monk (Clinic in Sports Medicine, 2005, circadian dip). Every recommendation has a source URL behind it.

2. The integration is real — Apple HealthKit isn't a write-only afterthought. Vari reads your workouts the moment they land and rebalances your remaining slots. Run 5K? Plan adjusts before you finish your post-run shower.

3. The platform is open — Vari's calculators are also published as the first hydration MCP server (Model Context Protocol). They run inside Claude Desktop, Cursor, and any MCP-compatible client. Listed in Anthropic's official

MCP Registry as `io.github.getvari/vari-mcp`.

— Built for —

People who care about cognitive performance through the day. Athletes, knowledge workers running on coffee, parents managing a household's hydration, and anyone who's ever realised at 16:00 that the headache they've been ignoring is just dehydration.

People with specific clinical contexts: pregnancy, postpartum, CKD with fluid restrictions, athletes with quantifiable sweat losses. Vari's calculators have separate models for each, and the medical-context tools include a disclaimer recommending you confirm with your provider.

— Free, no credit card —

Vari is free to download and use. Core hydration tracking, daily goal, smart schedule, drink logging, Apple Health two-way sync — all included. Premium (optional, monthly or yearly) unlocks Day-3 Insights, time-of-day pattern detection, the Weekly Story, and the Family Hydration dashboard.

— Get Vari —

📱 iPhone: free on the App Store — [getvari.app](https://getvari.app)

🌐 Free hydration calculators: [getvari.app/tools](https://getvari.app/tools/water-intake-calculator)

🤖 MCP server for Claude / Cursor: `npx -y @getvari/mcp` —

[github.com/getvari/vari-mcp](https://github.com/getvari/vari-mcp)