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The Prediction API is the read API for prediction-market data: tick-level YES/NO price history, the instrument catalogue, and full-text search across it. Use it to discover contracts, enumerate the outcomes under an event, and back charts or models with historical prices.

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Environments

These endpoints are available in two environments, selectable from the server dropdown in the playground on each endpoint page: Paths, parameters, and response shapes are identical in both. Staging carries its own catalogue and tick history, so symbols and event IDs will not match production.

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The three levels

Everything in this API is organized the same way, from broadest to narrowest: A contract’s symbol is the key used everywhere else: it is what you pass to the historical-data endpoints, and what search returns.

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Historical data

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Working with this API

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Prices are decimal strings

yesPrice, noPrice, and tickSize are exact decimals serialized as JSON strings ("0.54", not 0.54). Parse them with a decimal type. Reading them into a binary float loses precision at the tick sizes these contracts trade at.

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Search trails the catalogue

Search results come from an index that lags the catalogue by seconds. Use a hit’s symbol as a key, then read anything that must be current — state, tradable — from Get Event Contracts. Do not act on a hit’s own fields.

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Venue times carry no zone

expectedPayoutTime, expectedLastTradeTime, and expectedResolutionTime are venue wall-clock times. The upstream feed carries no time zone, so the trailing Z is a label rather than a conversion — do not shift these into local time.

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Response envelope

Every response uses the same envelope. On success:
On failure, success is false and error is a structured object with a categorical type (VALIDATION, NOT_FOUND, INTERNAL, EXTERNAL_SERVICE, …), a machine-readable code, and a human-readable message. Branch on type and code; message text is not fixed.
A 502 means the upstream data store or search index was unavailable — retry it; it does not indicate a bad request.

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Common uses

  • Discover contract symbols and event IDs with search before pulling historical ticks.
  • Enumerate every strike under an event, or the full event/contract tree under a base event.
  • Pull YES/NO tick history for one or many contracts to drive charting and modeling workflows.
  • Re-read state and tradable from the catalogue before acting on a symbol found through search.