API reference

Price history

Price over time for one outcome: OHLC candles built from the live quote stream where TPM has it, otherwise polled snapshots.

When to use it

Draw a price chart for an outcome.
Measure how far a price moved over a window.

Get outcome_id from an outcome's id in event detail. Without it you get the leading outcome.

GET/api/public/v1/events/{slug}/historyAPI key required

Get price history

source tells you where points come from: TPM's streamed candles (quote_candles), the venue's own price history for markets TPM doesn't stream (venue_history), both (mixed), legacy polls (snapshots) or nothing (none).

Parameters

Name	In	Type	Required	Default	Description
slug	path	string	Yes	—	Event slug.
outcome_id	query	string	No	—	Outcome `id` from `/events/{slug}`. Defaults to the leading outcome.
hours	query	integer	No	168	How far back, in hours. Default 7 days, max 4320 (180 days).
interval_minutes	query	integer	No	—	Candle width, 1 to 1440 minutes. Chosen automatically when omitted.

Request

curl -s 'https://api.thepredictionmarkets.com/api/public/v1/events/democratic-presidential-nominee-2028/history?outcome_id=5c66f06e-dcac-44fa-93af-ba710d2a9ed2&hours=24&interval_minutes=60' \
  -H 'X-API-Key: tpm_demo_key_authorized_2026'

Response

Example 200 response. Values are illustrative and change over time.

200 OK

{
  "data": {
    "event_slug": "democratic-presidential-nominee-2028",
    "outcome_id": "5c66f06e-dcac-44fa-93af-ba710d2a9ed2",
    "source": "quote_candles",
    "interval_minutes": 60,
    "points": [
      {
        "timestamp": "2026-10-21T06:00:00Z",
        "probability": 0.16,
        "open": 0.15,
        "high": 0.16,
        "low": 0.15,
        "close": 0.16
      },
      {
        "timestamp": "2026-10-21T07:00:00Z",
        "probability": 0.16,
        "open": 0.16,
        "high": 0.17,
        "low": 0.16,
        "close": 0.16
      }
    ]
  }
}

Response fields

Field	Type	Description
event_slug	string	The event.
outcome_id	string \| null	The outcome these points belong to.
source	string	`quote_candles` (streamed by TPM), `venue_history` (the venue's own price history, for markets TPM doesn't stream), `mixed` (venue history for the older part, streamed candles after), `snapshots` (legacy polls) or `none`.
interval_minutes	integer \| null	Candle width used.
points[].timestamp	string	Start of the candle, or time of the snapshot (UTC).
points[].probability	number \| null	The price at that time (the close, for candles).
points[].open, high, low, close	number \| null	OHLC for candles. May be `null` for snapshots.

Errors

HTTP	Code	When
404	not_found.event	No event has this slug.
400	validation.invalid_parameter	`hours` or `interval_minutes` is out of range.
401	auth.missing_key	No `X-API-Key` header was sent.
401	auth.invalid_key	The key is wrong or was revoked.
429	rate_limit.per_second	Too many requests this second. Wait for `Retry-After`.

404 not_found.event

{
  "error": {
    "code": "not_found.event",
    "message": "Event not found",
    "request_id": "0f8969a6-0968-4d7c-9cbb-de379e8c19c4"
  }
}

All codes are listed on the errors page.

Try it

Runs a live request from your browser. Pre-filled with the shared demo key (5 requests per second for everyone); paste your own key for steadier results.

Request URLX-API-Keyslug*pathoutcome_idqueryhoursqueryinterval_minutesquery

HTTP: —Time: —Rows: —Remaining this second: —Request: —

Press Send to run this request.

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Get your free API key

One key gives you Kalshi and Polymarket events, prices with freshness, price history, cross-venue gaps and the live quotes WebSocket.

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