"output": "json" and those numbers come back as fields: the odds on each outcome, bid and ask with their sizes, the last trade, volume, open interest and the rules it settles on. Prices are live at the time of the request, and you don’t need a Kalshi account. Each link costs 1 credit, and big lists cost a little more (credits).
Example
result, shortened to one market:
0.22 is 22 cents a contract. Kalshi counts volume in contracts, which volumeUnit says on every result. Each market also has its full rules, strike, settlement sources, tick size, the taker fee per contract and, once it settles, the result. The event has links to Kalshi’s rulebook and contract terms.
Links that work
Spidra reads these from Kalshi’s public market data, so the slug in a link doesn’t matter, only the tickers do. Strike ladders often have many rungs nobody trades. Add
activeOnly=true to a category, browse or search link to drop them.
Leaderboards
valueUnit on the result says what value is: dollars for profit, contracts for volume.
Compare with Polymarket
Addcompare=polymarket,polymarket-us to a category, browse or search link, and Spidra finds the same questions on each venue and puts their prices side by side, with the gap that’s left after both venues’ fees. It works the same way as comparing from Polymarket. A search for fed matched 18 pairs and cost 3 credits, 1 for each venue it read.
Credits
- Each link is 1 credit.
- Lists include 100 events in that credit, and trades, posts and leaderboards include 100 rows. Each further 100 is 1 more.
- Price history includes 1,000 points, and each further 1,000 is 1 more.
- A compare link costs 1 credit for each venue it reads. The matching is free.
Limits
- Prices are what Kalshi shows at the moment of the request, which
fetchedAtrecords. - Kalshi’s leaderboard stops at 100 ranks.
- A trader’s open positions are only shown to signed-in Kalshi users, so trader results don’t include them.
Templates
Templates cover the common Kalshi jobs, such as election odds, sports odds, weather markets, markets closing soon, odds history, big trades and the leaderboard, plus a prediction market arbitrage finder that works across Kalshi and Polymarket.Check Kalshi’s terms before you collect data from it. You’re responsible for how you use what you collect.