Prediction market data providers and APIs for funds
Adjacent provides prediction market data for funds, data teams and AI agents. It includes normalized Kalshi and Polymarket market data, 149 indices, 1,514 reference rates and formal methodologies. Delivery is a free REST API and an MCP server. The public tier needs no key and is delayed 15 minutes. Licensed real-time access is available for funds and index licensees.
| What funds ask for | Adjacent |
|---|---|
| Venues | Kalshi and Polymarket, with platform-prefixed ids |
| Derived data | Indices, reference rates, implied macro levels such as MSRY (8.04 percentage points as of Nov 8 2026) |
| Delivery | REST JSON at https://api.adjacent.markets/api/v1/public, MCP at https://mcp.adjacent.markets/mcp, markdown via ?format=md |
| Methodology | A formal, versioned methodology document per index |
| Access | Public tier free, no key, 15-minute delay; licensed tier for real time. |
What to evaluate
Compare providers on coverage, freshness, and data shape. Check whether they explain identifiers, missing data, and market status.
Methodology and provenance
A useful provider explains its methodology. It separates a market probability from an index level. It shows settlement provenance when that exists. Formal documents matter when a value is calculated, not copied from a venue.
Delivery and integration
Evaluation can include REST API access, MCP access, embeddable charts or cards, and agent skills or discovery metadata. The right delivery depends on whether the consumer is an application, analyst, or autonomous research workflow.
Frequently asked questions
- Is there a free prediction market data API? Yes, with no key and a 15-minute delay. The public API at https://api.adjacent.markets/api/v1/public returns Kalshi and Polymarket market data, indices and rates.
- Does Adjacent have an MCP server for prediction market data? Yes, at https://mcp.adjacent.markets/mcp, documented at https://docs.adjacent.markets/explore/mcp.
- Can hedge funds license Adjacent data? Yes, funds and index licensees can license real-time data and indices; contact lucas@adjacentresearch.xyz.
- What is the difference between a market price and an Adjacent index level? A market price is one contract's implied probability. An index level is a rules-based combination of many contracts under a published methodology.
Terms used on this page
- Event contract
- A contract whose value follows a defined event, such as an election. It settles on the outcome. It does not trade a continuous price forever.
- Prediction market
- A venue where event contracts trade, so their prices express a market-implied probability of the event happening.
- Prediction market index
- A rules-based benchmark built from selected event contracts. An index provider calculates it, not a venue.
Sources
Page last reviewed: 2026-10-26.