Adjacent API

Adjacent gives you one place to work with prediction-market data from Kalshi and Polymarket. Use it to build research tools, track markets, compare prices, or give an AI agent reliable market data.

You can start with delayed public data or use an API key for realtime data and the full catalog.

Start with the API reference

Browse every endpoint with schemas, examples, and a live cURL request.

Pricing

Compare data access, quotas, and plan limits.

Choose what you need

Market data. Find markets and events, then read prices, trades, quotes, and candles. Start with Market data.

Indices. Use an index when you need a single measure built from many prediction markets. Start with Indices.

Reference rates. Compare the same market across venues or across rolling contracts with one price series. Start with Reference rates.

News. Find stored articles and connect them to markets, indices, and filings. Start with News.

Filings. Browse CFTC industry filings and follow status changes, attachments, and related markets. Start with Filings.

AI agents. Connect an agent through MCP instead of teaching it every REST endpoint. Start with MCP server.

Base URL

1https://api.adjacent.markets

All endpoints use the /api/v1/ prefix.

Authentication

The anonymous /api/v1/public/* tier needs no token and returns data delayed by 15 minutes.

Realtime endpoints require a bearer token. Use a session token from the app or an API key with the read scope for the resource you are calling.

12curl -H "Authorization: Bearer YOUR_TOKEN" \
  https://api.adjacent.markets/api/v1/rates

API keys

Create and manage keys in the app under Settings → API keys. Choose scopes that your account can grant, then copy the secret because it appears only once.

Send the key as a bearer token:

12curl -H "Authorization: Bearer ak_your_key" \
  https://api.adjacent.markets/api/v1/rates

…or as an api_key query parameter:

1curl "https://api.adjacent.markets/api/v1/rates?api_key=ak_your_key"

A key can reach only the endpoints covered by its scopes. Other requests return 403.

Need help choosing?

Start with the public tier if you are exploring the data or building a prototype. Use an API key when you need realtime values, deeper history, news, or higher request limits. If you are not sure which endpoint fits your use case, contact support.