WebSocket overview

Stream real-time, normalized prediction market data over WebSocket. One connection gives you cross-venue orderbooks, trades, and probability distributions from both Kalshi and Polymarket — no venue-specific code needed. Data is addressed by what, not where. You subscribe to dist:fomc-2026-04-29 or dist:btc-5m-2026-03-24-0830-et, not a venue-specific ticker. Both venues arrive on the same channel, tagged by venue field. Two feeds are available:

Macro feed — FOMC, CPI, NFP, GDP, unemployment, equities, commodities
Crypto feed — BTC and ETH prediction markets enriched with real-time Binance spot/futures data

wss://feeds.oddpool.com/ws

Authentication

Send an auth message with your API key after connecting. The server responds with your tier and limits.

// Send
{"action": "auth", "api_key": "oddpool_abc123..."}

// Response
{
  "type": "auth",
  "status": "ok",
  "user_id": 42,
  "tier": "pro",
  "limits": {
    "max_events": 10,
    "max_connections": 3,
    "channels": ["dist", "book", "trade", "snapshot"]
  }
}

max_events: 0 means unlimited (Premium tier and above). Any positive number is the cap. Subscribe to channels by event. Events count as concurrent subscriptions — unsubscribing frees up slots.

Channel format

Format	Example	Scope
`{type}:{event_key}`	`dist:fomc-2026-04-29`	All outcomes for that event
`{type}:{event_key}:{outcome}`	`book:fomc-2026-04-29:hold`	Single outcome

Example

// Subscribe to multiple channels at once
{"action": "subscribe", "channels": ["dist:fomc-2026-04-29", "book:fomc-2026-04-29:hold"]}

// Response
{"type": "subscribed", "channels": ["dist:fomc-2026-04-29", "book:fomc-2026-04-29:hold"]}

// Unsubscribe
{"action": "unsubscribe", "channels": ["book:fomc-2026-04-29:hold"]}

channels lists the channels that were actually subscribed. If any submitted channel was dropped, the response also includes a rejected array — only present when there is at least one rejection. Each entry has a channel and a reason:

`reason`	When it fires
`unknown_event_key`	The `event_key` is not currently served. Use Catalog to find valid keys; venue-native IDs (Kalshi market tickers, Polymarket condition IDs) are not event keys.
`unknown_channel_type`	The prefix is not one of `dist`, `book`, `trade`, `snapshot`.
`missing_event_key`	The channel string has no `event_key` after the type prefix.

// Mixed batch
{"action": "subscribe", "channels": ["dist:fomc-2026-04-29", "dist:not-a-real-event"]}

// Response
{
  "type": "subscribed",
  "channels": ["dist:fomc-2026-04-29"],
  "rejected": [
    {"channel": "dist:not-a-real-event", "reason": "unknown_event_key", "event_key": "not-a-real-event"}
  ]
}

dist, book, and trade are change-driven — messages emit only when the underlying state changes, so an idle channel is normal during quiet windows. For current state on connect, also subscribe to snapshot:{event_key}, which delivers a full state message every 60 seconds.

Getting started

WebSocket feeds

Whale tracking

Arbitrage

Search

Historical bars

Kalshi

Polymarket

Authentication

Channel format

Example

​Authentication

​Subscribe and unsubscribe

​Channel format

​Example

​Subscribe response shape

Authentication

Subscribe and unsubscribe

Channel format

Example

Subscribe response shape