For builders

Kalshi API alternatives: pick by job, not by brand

“Kalshi API alternative” means three different things: a different venue to execute on, a broader market-data feed, or a kind of data Kalshi structurally cannot offer — wallet-level intelligence. This page maps all three honestly, including where CrowdIntel is not the answer.

Short answer

Execution on the on-chain venue: Polymarket's official CLOB API. One API across both venues: Synthesis. Wallet-level intelligence — trader track records, insider signals, funding clusters: CrowdIntel, which only exists because Polymarket settles on-chain. On Kalshi, that data isn't private-tier expensive — it's structurally unavailable.

Job 1: execute trades programmatically

Kalshi's own API is the only way to trade Kalshi. The on-chain equivalent is Polymarket's official CLOB API — order books, prices, order placement, settled in USDC on Polygon. If you want one integration covering both venues, Synthesis (synthesis.trade) exposes unified endpoints for wallet creation, orders, positions, and WebSocket streams across Polymarket and Kalshi.

Job 2: market data and prices

Both venues publish market-level data through their official APIs. The difference is depth of history and openness: Polymarket's complete trade record lives on a public blockchain anyone can index, while Kalshi's book is internal. If your model needs years of granular fill-by-fill history, the on-chain venue is the one where that history is verifiable.

Job 3: wallet-level intelligenceour lane

Who is behind the flow? Are they good? Are five “independent” wallets actually one funder? Kalshi's private ledger makes these questions unanswerable by anyone. On Polymarket they're answerable from public data — and CrowdIntel has done the work: 1.7B trades indexed since 2020, 3M wallets profiled with resolved-outcome PnL and an 8-signal suspicion score, funding graphs traced, all served over a read-only REST API, webhooks, and an MCP server for AI agents.

FAQ

What's the best Kalshi API alternative?

Depends on what you're building. For trading a different venue programmatically, Polymarket's official CLOB API is the direct equivalent on the on-chain side. For one API spanning both venues, Synthesis (synthesis.trade) exposes unified Polymarket + Kalshi endpoints for wallets, orders, and streaming data. For wallet-level intelligence — who's trading, how good they are, whether wallets are coordinated — CrowdIntel is the specialist, and that class of API only exists on Polymarket because its trades settle publicly on Polygon.

Why can't I get wallet-level data from Kalshi's API?

Kalshi is a CFTC-regulated exchange running on an internal ledger with a private order book. No public per-trader record exists, so no third party can build wallet histories, win rates, or coordination analysis there. Polymarket settles every trade on Polygon in public — that structural difference is what makes wallet forensics possible at all.

Does CrowdIntel cover Kalshi?

No — Polymarket only, deliberately. CrowdIntel's value is computed from on-chain data: 1.7B indexed trades, resolved-outcome PnL, funding-graph clusters, insider scores across 3M wallets. Kalshi publishes no equivalent data, so any 'Kalshi wallet intelligence' product would be guesswork. We'd rather be complete on one venue than shallow on two.

I'm leaving Kalshi's API — what does CrowdIntel actually give me?

A read-only REST API (OpenAPI 3.1, Bearer auth, cursor pagination) over wallets, insider signals, the trade tape, markets, leaderboards, funding clusters, hosted backtests, and webhooks — plus an MCP server so AI agents can query the same data. REST ships on Terminal ($99/mo); MCP starts on Pro ($29/mo). Execution isn't included: pair it with Polymarket's official API for orders.

Building on prediction-market data?

Start with the Polymarket API for bots overview, the API reference, or the venue-level Polymarket vs Kalshi comparison. Plans on pricing.