Market Data

Compare L1, L2, and L3 order book views, then choose between REST snapshots and WebSocket updates for your integration.

L1, L2, and L3 describe how much of an order book you can see. The examples below are illustrative; use the API reference for the exact response shape.

L1: Best Prices

L1 shows the best available bid and ask with aggregate size, plus the latest trade.

Best bid   $0.54 × 120 contracts
Best ask   $0.56 ×  80 contracts

Use L1 when you need the current spread but not the depth behind it.

L2: Price Levels

L2 shows the full price ladder with quantity aggregated at each price level. It does not expose individual orders.

{
  "orderbook": {
    "ticker": "UDX-EXAMPLE-MARKET",
    "bids": [
      ["0.54", "120"],
      ["0.53", "300"]
    ],
    "asks": [
      ["0.56", "80"],
      ["0.57", "250"]
    ]
  }
}

Each pair is [price, quantity]. UDX prices the book from the YES side.

Use L2 to display depth, estimate available liquidity, or recover a local order book. The public REST snapshot and WebSocket stream currently use this model.

L3: Individual Orders

L3 shows every individual resting order, including its size, updates, and FIFO queue position. Use L3 only when the published interface provides it.

$0.54 bid
  Order A    50 contracts
  Order B    70 contracts

When L3 is available, use it when your integration needs order-level queue information.