Narwhal API
One schema for economic, central bank, metals and energy odds across both venues.
Kalshi vs Polymarket API
Compare direct access to Kalshi and Polymarket with Narwhal's shared schema. Both venues publish market data over REST without a key, but WebSocket authentication, SDKs and response formats differ.
Decision
Choose Narwhal for both venues under one key and schema on supported economic and commodity topics. Choose a venue's own API when you need its broader market coverage or trading-oriented data.
Provider shortlist
This compares data interfaces and supported markets rather than trading eligibility. Narwhal API is owned and operated by Nusantara Ventures, LLC.
Kalshi API
Kalshi-native markets, events, order books and candlestick history.
Polymarket API
Polymarket-native discovery, order books, prices and activity.
Compare the options
Best fit is not feature parity. Check the evidence and limitation together.
| Provider | Best for | Evidence checked | Important limitation |
|---|---|---|---|
| Narwhal API | One schema for economic, central bank, metals and energy odds across both venues. | REST and hosted MCP share a key and quota; Basic and Pro include WebSocket odds. | Free returns the previous day's close; sports, politics and crypto markets are not covered. |
| Kalshi API | Kalshi-native markets, events, order books and candlestick history. | Official Python and TypeScript SDKs support its REST and WebSocket APIs. | WebSocket needs authentication even for public channels; historical retention is not stated. |
| Polymarket API | Polymarket-native discovery, order books, prices and activity. | Official TypeScript, Python and Rust SDKs accompany three REST hosts and a public WebSocket market channel. | Gamma returns outcome labels, prices and token IDs as JSON-encoded strings; normalisation remains your application's job. |
Choose by requirement
Public data access
Both venues expose public REST market data without a key. Kalshi requires authentication for public WebSocket channels; Polymarket publishes a public market channel.
History and client libraries
Kalshi documents 1-minute, 1-hour and daily candlesticks without stating retention. Its SDKs cover Python and TypeScript; Polymarket also publishes Rust.
One schema and MCP
Choose Narwhal for supported topics across both venues and hosted MCP. Neither exchange has an official MCP server in the cited documentation.
Sources and review date
Each detailed provider page lists the first-party documentation used, its evidence boundaries, and its review date.
Reviewed: