REST API / Prices / Unified Orderbook

Unified Orderbook

Live unified orderbook for a market match group across all platforms. Aggregates bid/ask depth from Kalshi, Polymarket, and Opinion into a single combined view. Use the group_id from the matching-markets or events endpoints.

GET/v2/unified-orderbook

Query Parameters

group_idintegerRequired

Market match group ID (required). Get this from /v2/matching-markets, /v2/events, or /v2/search.

Response Schema

event_namestring

Event name for the matched group.

candidatestring

Candidate / group title.

platformsobject

Per-platform orderbook data.

kalshiobject

Kalshi orderbook (if available).

ticker / token_idstring

Platform-native identifier.

market_idstring

Platform market ID.

timestampnumber

Unix timestamp in milliseconds.

bidsarray[]

Bid levels [price, size], sorted descending.

[0]number

Price in cents (0-10000).

[1]number

Size (contracts) at this level.

asksarray[]

Ask levels [price, size], sorted ascending.

[0]number

Price in cents (0-10000).

[1]number

Size (contracts) at this level.

polymarketobject

Polymarket orderbook (if available).

ticker / token_idstring

Platform-native identifier.

market_idstring

Platform market ID.

timestampnumber

Unix timestamp in milliseconds.

bidsarray[]

Bid levels [price, size], sorted descending.

[0]number

Price in cents (0-10000).

[1]number

Size (contracts) at this level.

asksarray[]

Ask levels [price, size], sorted ascending.

[0]number

Price in cents (0-10000).

[1]number

Size (contracts) at this level.

opinionobject

Opinion orderbook (if available).

ticker / token_idstring

Platform-native identifier.

market_idstring

Platform market ID.

timestampnumber

Unix timestamp in milliseconds.

bidsarray[]

Bid levels [price, size], sorted descending.

[0]number

Price in cents (0-10000).

[1]number

Size (contracts) at this level.

asksarray[]

Ask levels [price, size], sorted ascending.

[0]number

Price in cents (0-10000).

[1]number

Size (contracts) at this level.

combinedobject

Unified orderbook aggregated across all platforms.

bidsarray[]

Aggregated bid levels across all platforms.

[0]number

Price in cents (0-10000).

[1]number

Size (contracts) at this level.

asksarray[]

Aggregated ask levels across all platforms.

[0]number

Price in cents (0-10000).

[1]number

Size (contracts) at this level.

Error Responses

All errors return the same envelope. The code field is stable and programmatically branchable; error and message are human-readable. errors[] is present only on validation failures with field-level detail. See the full error code reference →

successboolean

Always `false` on error responses.

errorstring

Short, human-readable title (e.g. 'Invalid API Key.').

messagestring

Human-readable explanation for the error. Safe to surface in UIs.

codestring

Stable, hierarchical machine-readable code (e.g. 'validation.invalid_enum'). Use for programmatic handling.

doc_urlstring

Link to this code's entry in the Error Reference.

errorsobject[]

Optional. Present only on validation failures with field-level detail.

fieldstring

Name of the offending parameter.

codestring

Field-level machine code.

messagestring

Human-readable explanation.

Authentication

API Key

To secure your requests, we strongly recommend passing your API key via the X-API-Key header. This prevents sensitive keys from being exposed in access logs or browser history.

Request HeaderX-API-Key: pmx_test_5e8f...

Rate Limits

API rate limits are enforced based on the tier associated with your API key. Limits are tracked on two dimensions: requests per second and requests per month. Each completed request counts toward the global monthly quota. Separate endpoint-group monthly limits (matched markets, arbitrage, EV) only advance when the response body has success: true.

Usage is returned on responses via headers such as:

Response Headers (global)X-RateLimit-Limit-Second: 10X-RateLimit-Remaining-Second: 9X-RateLimit-Limit-Month: 1000X-RateLimit-Remaining-Month: 842Example (endpoint-group, when applicable)X-RateLimit-Limit-Arb-Month: 500X-RateLimit-Remaining-Arb-Month: 412

If you exceed a rate limit, the API returns a 429 status with a Retry-After header indicating when you can resume.

Request

Live API Key

Demo Mode

Verified

Parameters

Group IDRequired

Response

—

Click EXECUTE to send a request →