What is Isocast?
Isocast is a pay-per-signal API for Polymarket weather markets, built for AI agents and developers. The instant a city’s observed daily-high temperature crosses into a new Polymarket temperature bucket, Isocast emits a structured JSON signal — the city, the market URL, the old and new reading and bucket, and the live odds for every bucket. Agents buy prepaid signal bundles with USDC on Base over the x402 protocol — no accounts, no API keys — and receive each signal on Telegram or pull it over HTTP.
What you get
GET /v1/citiesAll tracked cities plus each city’s latest signal sequence number.
GET /v1/cities/:slugOne city, today’s target date, and its Polymarket market URL.
GET /v1/sample?city=SLUGA real seq-1 signal payload so you can learn the exact shape for free.
GET /v1/signals?city=SLUG&count=NBuy a prepaid bundle of live signals over x402; each crossing draws it down.
Signals are sold in prepaid bundles over x402 (USDC on Base). The per-signal price falls with bundle size, from $0.005 down to $0.0035 at the largest bundle. Minimum spend is $0.01. See the pricing table for every tier.
How agents pay
Request a bundle with no payment and Isocast answers HTTP 402 with the terms. Your wallet signs a USDC payment on Base — binding the payer, city, and count — and you retry with the payment header. One settlement buys N signals; each is then delivered for free against the prepaid balance.
# Buy a bundle — 402 with terms, then retry with a signed payment.
$ curl -i "https://api.isocast.dev/v1/signals?city=nyc&count=100"
HTTP/1.1 402 Payment Required
# wallet signs a USDC payment on Base, binding (payer, city, count)
$ curl "https://api.isocast.dev/v1/signals?city=nyc&count=100" \
-H "X-PAYMENT: <x402 signature>"
HTTP/1.1 200 OKAlternatives
Raw NOAA / weather APIs. Public weather services give you observed and forecast temperatures for free, and are the right choice if you want to build everything yourself. Isocast does the shaping on top: it maps the observation onto the specific Polymarket temperature buckets, detects the exact moment of a bucket crossing, attaches the live per-bucket odds and the market URL, and delivers that as an immutable, replayable signal — so an agent consumes a decision-ready event rather than a raw temperature stream it must interpret itself.
Isocast provides informational data signals only — not financial, investment, or betting advice. Signals may be delayed, inaccurate, or incomplete.
FAQ
- Does Isocast need an API key or account?
- No. Isocast has no signups or API keys. You poll the free endpoints directly, and buying signal bundles is a single x402 payment — a wallet signs a USDC transfer on Base, no account attached.
- How do agents pay for Isocast signals?
- Request a signal bundle and you get an HTTP 402 challenge with the terms. Your wallet signs a USDC payment on Base, binding the payer, city, and count, and you retry with the payment header. A single settlement buys N signals; each is then delivered against the prepaid balance. Minimum spend is $0.01 USDC.
- How fresh are the signals, and how are they delivered?
- A signal fires the instant a city’s observed daily-high temperature crosses into a new Polymarket temperature bucket. Signals are pushed to your agent’s Telegram, and a pull API (GET /v1/signals) is available for backfill. Signals are immutable and sequentially numbered so a crashed consumer can replay.
- Are Isocast signals financial advice?
- No. Isocast provides informational data signals only — a descriptive record of a physical observation, never advice or a recommendation to place any wager or trade. You are solely responsible for your own decisions.