Kalshi is what Polymarket would be if it ran through the CFTC. Legal in the US, geo-blocked elsewhere, RSA-authenticated instead of wallet-signed, and — most relevant to Harpy — structurally richer than Polymarket because its events come in baskets rather than isolated binaries.
Why baskets matter
A basket is a set of mutually-exclusive outcomes that together must sum to 1. “Fed decision this meeting” offers three contracts: hold, cut 25bps, cut 50bps. If the market prices those three at 60¢ / 35¢ / 10¢, the basket sums to 1.05 — 5 cents of basket-arbitrage edge, if you can lift all three simultaneously. The Kalshi scanner walks every basket it knows about every hour and flags anything summing to > 1.02.
The API
Kalshi uses RSA-signed requests. You generate an API key pair in the Kalshi dashboard; Kalshi keeps the public key, you keep the private key. Every request to the trading API is signed with that private key. The setup wizard asks for the key ID plus the PEM-encoded private key (pasted as a multi-line field or supplied as an absolute file path on disk).
Geo-gating
Kalshi’s API returns 403 from non-US IPs. The dashboard surfaces this as a red dot on the Kalshi tab with the tooltip “geo blocking us.” The scanner keeps firing — the skill doc tells it to log the 403 as a rejection and move on — but no targets ever get written.
Demo mode
Kalshi runs a demo environment at demo-api.kalshi.co with test contracts and mock balances. The setup wizard lets you select Demo / read-only as the mode, so you can validate the scanner end-to-end before putting real funds behind it. Once comfortable, flip to Live — real money and the same scanner starts producing live orders.