Parametric weather cover exists for farmers and big event organisers, and some ski resorts and travel firms run one-off "money back if it snows or rains" stunts. None of it is a self-serve tool a gelato shop or a tour guide can switch on in two minutes. Rain Check is a promotion, not insurance: the shop funds its own pool, the customer pays nothing extra, and a contract reading public weather data pays out automatically.
The data it runs on
Free weather data from Open-Meteo: the forecast API for slot pricing and its historical weather API (about 80 years of hourly reanalysis) to estimate how often a threshold is hit for a given place, month and time of day. On the day, the monitor polls Open-Meteo’s 15-minute precipitation for the shop’s grid cell (native 15-minute data in some regions, interpolated from hourly elsewhere). Limits: model data is a grid estimate, not a rain gauge on the shop’s roof, and a passing shower can be missed. Fallback: if the source is down or readings look wrong, the payout waits for a second source (a national weather service feed or a nearby station via Meteostat) and the shop can always pay manually.
1. The mission
Turn bad weather from a lost day into a reason to book. Small outdoor businesses everywhere lose customers to forecasts. Rain Check lets them make a promise the weather itself keeps.
2. Why people can’t resist it
Loss aversion flipped. "What if it rains?" stops being a reason to wait. Booking now feels risk free.
The rain lottery. Customers secretly hope for a shower. Watching the meter on the day is fun.
Trust without asking. Nobody has to claim, argue or send a photo. The payout just arrives.
3. How it works for real
Login: email for shops and customers; passkey smart wallets (Coinbase Smart Wallet or Privy) created behind the scenes. Gas sponsored by a paymaster on Base.
Pool: the shop deposits USDC into a promotion contract on Base with its rules: place, threshold in mm, refund percent, maximum payout. The pool pauses new Rain Checks when it runs low.
Book: customers pay by card or local rails on-ramped to USDC, or the shop’s own checkout calls the contract through x402 per booking.
Oracle: a small worker (or Chainlink Functions) fetches Open-Meteo readings for the slot, signs the total, and posts it on-chain. Two sources must agree above the threshold.
Payout: the contract sends the refund to the customer’s wallet within minutes of the slot ending; off-ramp to bank or e-wallet.
AI: a fast model (Gemini Flash via OpenRouter) writes the promo copy and poster text; a frontier LLM (Claude) explains pricing to the shop in plain words. The payout logic is plain code, never an LLM.
4. Cost per use
Near zero; the shop funds the pool. Weather calls are free on Open-Meteo’s non-commercial tier, with a low-cost commercial plan at scale. Oracle post and payout on Base cost fractions of a cent, sponsored.
Free for customers.Shops: free up to 50 Rain Check bookings a month, then $19 per month or 2% of pool payouts. Revenue also from booking-platform integrations.
5. Growth loop
Each payout is a story the customer shares ("it rained, the gelato shop paid me back"), and each shop puts a Rain Check badge on its window and listings. Customers then look for the badge, and nearby shops copy the promotion. Every Thursday the shop gets next week's rain calendar to arm in one tap, and a running ledger of payouts against extra sales shows the promotion paying for itself, so owners come back each week to plan the next one.
6. Risks and guardrails
Not insurance: the customer pays no premium and gets no indemnity; it is a conditional discount funded by the shop. Wording reviewed per country.
Pool drain: per-day and per-month payout caps; the expected cost is shown before launch.
Bad data: two-source agreement, readings logged publicly, manual override by the shop.
Gaming: bookings close 24 hours before the slot, so nobody books only after a storm is certain.
7. MVP build order
Promotion contract on Base Sepolia: pool, rules, payout, caps.
Pricing estimate from Open-Meteo historical data for a place, month and slot.
Booking page with email login and a Rain Check ticket.
Day-of monitor and the oracle worker; then the shop dashboard.