HIP-4 outcome markets live under /v1/hyperliquid/hip4/*. Use this family when the product needs binary outcome-market data, side-level order books, trades, candles, open interest, or probability-like mark and mid values. For coverage windows and history context, start with the HIP-4 historical data API page.
HIP-4 mark_price and mid_price values are implied probabilities in the [0, 1] range. Do not treat them as USD prices.
Discover an outcome first
Each outcome groups a Yes side and a No side. List them before you pull a book or trades:
curl "https://api.0xarchive.io/v1/hyperliquid/hip4/outcomes?limit=1" \
-H "X-API-Key: $OXARCHIVE_API_KEY"
{
"success": true,
"data": [
{
"outcome_id": 0,
"name": "Recurring",
"class": "priceBinary",
"underlying": "BTC",
"expiry": "2026-05-03T06:00:00Z",
"target_price": 78213,
"period": "1d",
"side_specs": [
{ "side": 0, "name": "Yes", "coin": "#0", "asset_id": 100000000, "display_title": "BTC above 78,213 on May 3 at 06:00 UTC? — Yes" },
{ "side": 1, "name": "No", "coin": "#1", "asset_id": 100000001, "display_title": "BTC above 78,213 on May 3 at 06:00 UTC? — No" }
],
"is_settled": true,
"status": "settled",
"display_title": "BTC above 78,213 on May 3 at 06:00 UTC?"
}
],
"meta": { "count": 1, "next_cursor": "...", "request_id": "req_4c8a1f02e9b7d350" }
}
- An outcome groups two sides:
side 0 is Yes (coin #0), side 1 is No (coin #1). Use that side coin (URL-encoded, e.g. %230) for the order-book and trade routes.
target_price and expiry define the binary; is_settled and status say whether it resolved. Re-check those fields with /v1/hyperliquid/hip4/outcomes/{outcome_id} or /v1/hyperliquid/hip4/outcomes/by-slug/{slug} to see when an outcome settles.- Use
/v1/hyperliquid/hip4/questions and /v1/hyperliquid/hip4/questions/{question_id} when the workflow starts from question metadata instead of an outcome side.
Request parameters
Outcome discovery (/v1/hyperliquid/hip4/outcomes):
| Parameter | In | Type | Required | Description |
|---|
is_settled | query | boolean | No | Filter by settlement; omit for both live and settled |
limit | query | integer | No | Max results. Default 100, max 1000 |
cursor | query | string | No | Pagination cursor |
coin id as {symbol} (e.g. %230 for the Yes side) plus the usual window and depth parameters.
Question discovery (/v1/hyperliquid/hip4/questions) supports the same bounded-list pattern as outcomes. Use /v1/hyperliquid/hip4/questions/{question_id} for one question, and /v1/hyperliquid/hip4/outcomes/by-slug/{slug} when the public question URL slug is the identifier you have.
Response fields
Each outcome in the data array:
| Field | Type | Description |
|---|
outcome_id | integer | Numeric outcome identifier |
name | string | Human-readable outcome name |
class | string | Outcome class, e.g. priceBinary |
underlying | string | Underlying asset for recurring price-binary outcomes |
target_price | number | Target price for the binary |
expiry | string | Settlement time (UTC) |
period | string | Cadence of a recurring market, e.g. 1d |
side_specs | array | Per-side specs, usually side 0 (Yes) and side 1 (No) |
is_settled | boolean | Whether the outcome has settled |
status | string | Lifecycle status (live, settled, …) |
side_specs entry has side (0 for Yes, 1 for No), name, coin (the #-prefixed id you pass as the symbol), and asset_id. The single-outcome route (/outcomes/{outcome_id}) also returns aggregated_oi with per-side open-interest contracts. HIP-4 order books and trades use the same fields as the core Order book and Trades schemas; only the symbol form differs, and mark_price and mid_price are implied probabilities in [0, 1], not USD.
Example
curl "https://api.0xarchive.io/v1/hyperliquid/hip4/orderbook/%230" \
-H "X-API-Key: $OXARCHIVE_API_KEY"
Use HIP-4 For
| Need | Where |
|---|
| Outcome discovery | HIP-4 outcomes and instruments (this page) |
| Question lookup | HIP-4 questions and outcome by slug routes |
| Side-level order book | Order books, HIP-4 tab |
| Outcome trades | Trades, HIP-4 tab |
| Probability history | Candles and Open interest, HIP-4 tab |
Stream it live
HIP-4 streams the side-level book and order events: hip4_orderbook, hip4_trades, hip4_open_interest, hip4_l4_diffs, and hip4_l4_orders. There is no HIP-4 funding, liquidation, or candle stream (only Lighter streams candles). Pass the outcome-side coin (URL-encoded, e.g. %230) as the symbol.
ws.send(JSON.stringify({ op: "subscribe", channel: "hip4_orderbook", symbol: "#0" }));
Export in bulk
HIP-4 side-level data exports under the standard schemas, delivered as Parquet with ZSTD compression: l2_orderbook ($6/GB, $10 minimum), l4_orderbook ($8/GB, $25 minimum), trades ($8/GB, $15 minimum), and oi ($1/GB, $5 minimum). Preserve the outcome and side context in every file. Build a selection in the Data catalog; columns and coverage keys are on Export schemas.
HIP-4 Request Checklist
Use this checklist before HIP-4 data enters charts, models, exports, or generated clients.
| Field | HIP-4 value |
|---|
| Namespace | /v1/hyperliquid/hip4/* |
| Identifier | Outcome ID, side identifier, or symbol from Endpoint Reference |
| Price handling | Treat documented mark and mid values as implied probabilities in [0, 1] |
| First probe | Outcome discovery, one order book, one trades page, or one OI request |
| Stop rule | Do not route outcome IDs through core Hyperliquid, Spot, HIP-3, or Lighter paths |
Routing Rule
Store the outcome identifier and venue family with every record. Run outcome discovery before assuming an identifier, then pull the side-level order book, trades, candles, or open-interest route that matches the workflow. For historical analysis, combine the request with Data quality and request-ID logging so probability series can be audited later. Keep the URL encoding intact in examples such as %230, and never compare a mid_price against a dollar-denominated BTC, ETH, or Spot price.
Next
Use Order books and Trades for the side-level routes (HIP-4 tab), Open interest for positioning, Data quality before HIP-4 data feeds a model, or Best Hyperliquid Data API for the family-selection context. 
