> ## Documentation Index > Fetch the complete documentation index at: https://platform.trendlinelabs.ai/llms.txt > Use this file to discover all available pages before exploring further. # Get a market's order book on one venue > A market's live L2 book on one venue: YES and NO ladders with at most `depth` levels a side. Prices are 0..1; sizes are in contracts. **The NO side** - `no_source: book`: the venue's own NO book, while it is live. - `no_source: derived`: computed as 1 - YES. Approximate on Polymarket, whose YES and NO are two real books. **Freshness** - `ts_ms`: when the book last changed, so a quiet live book can be old. - `age_ms`: how old the book is now; `max_age_s`: the oldest this venue's book may be before it is refused. **Errors** | Status | Code | When | |---|---|---| | 422 | `venue_unsupported` | A venue whose books are not served. | | 404 | `not_found` | Unknown market. | | 404 | `venue_not_listed` | The market has no leg on that venue. | | 410 | `market_closed` | The leg no longer trades. | | 503 | `dependency_unavailable` | Our store is unavailable. | | 503 | `upstream_unavailable` | No live book, no timestamp, a timestamp in the future, older than the venue's bound, or market data unreadable. | Any route can also answer 401, 403, 429, 500 or 503 `dependency_unavailable`, described on the Errors page. ## OpenAPI ````yaml /openapi.json get /public/v1/markets/{universal_id}/orderbook openapi: 3.1.0 info: description: >- Read-only prediction-market data across Polymarket, Kalshi, Limitless and predict.fun over REST. Every request sends your key as `Authorization: Bearer tl_live_…`; try any endpoint from its page. title: TrendlineLabs Public API version: '1' servers: - description: Production url: https://systems.trendlinelabs.ai security: [] tags: - description: 'Read back the key you are calling with: its scopes, tier and rate limit.' name: Your key - description: Events group markets across venues; each carries a `universal_id`. name: Events - description: One market's order book, price history and trades on one venue. name: Markets - description: Current prices for a set of markets in one call. name: Prices - description: Live cross-venue price gaps on the same market. name: Opportunities paths: /public/v1/markets/{universal_id}/orderbook: get: tags: - Markets summary: Get a market's order book on one venue description: >- A market's live L2 book on one venue: YES and NO ladders with at most `depth` levels a side. Prices are 0..1; sizes are in contracts. **The NO side** - `no_source: book`: the venue's own NO book, while it is live. - `no_source: derived`: computed as 1 - YES. Approximate on Polymarket, whose YES and NO are two real books. **Freshness** - `ts_ms`: when the book last changed, so a quiet live book can be old. - `age_ms`: how old the book is now; `max_age_s`: the oldest this venue's book may be before it is refused. **Errors** | Status | Code | When | |---|---|---| | 422 | `venue_unsupported` | A venue whose books are not served. | | 404 | `not_found` | Unknown market. | | 404 | `venue_not_listed` | The market has no leg on that venue. | | 410 | `market_closed` | The leg no longer trades. | | 503 | `dependency_unavailable` | Our store is unavailable. | | 503 | `upstream_unavailable` | No live book, no timestamp, a timestamp in the future, older than the venue's bound, or market data unreadable. | Any route can also answer 401, 403, 429, 500 or 503 `dependency_unavailable`, described on the Errors page. operationId: getOrderbook parameters: - description: >- no control, format, private-use, unassigned, line or paragraph separator character in: path name: universal_id required: true schema: description: >- no control, format, private-use, unassigned, line or paragraph separator character maxLength: 256 minLength: 1 title: Universal Id type: string - description: the venue whose book to read in: query name: venue required: true schema: description: the venue whose book to read enum: - kalshi - polymarket - limitless - predictfun title: Venue type: string - description: levels per side in: query name: depth required: false schema: default: 10 description: levels per side maximum: 10 minimum: 1 title: Depth type: integer responses: '200': content: application/json: example: age_ms: 1500 as_of_ms: 1791266400000 max_age_s: 1200 'no': asks: - price: 0.6 size: 150 bids: - price: 0.59 size: 310 no_source: book ts_ms: 1791266398500 universal_id: mk-btc-100k-2026 venue: kalshi venue_market_id: KXBTC-26DEC31-B100000 'yes': asks: - price: 0.41 size: 310 - price: 0.42 size: 90 bids: - price: 0.4 size: 150 - price: 0.39 size: 400 schema: $ref: '#/components/schemas/PublicOrderBook' description: Successful Response headers: Cache-Control: description: no-store on every answer schema: type: string X-RateLimit-Limit: description: >- requests allowed per window for this key; present once the key passed the limiter schema: type: integer X-RateLimit-Remaining: description: >- requests left in this window; present once the key passed the limiter schema: type: integer X-RateLimit-Reset: description: >- seconds until the window resets; present once the key passed the limiter schema: type: integer X-Request-Id: description: >- this request's id (yours, when you sent X-Request-Id); equals the envelope's request_id schema: type: string '401': content: application/json: schema: $ref: '#/components/schemas/PublicError' description: 'unauthorized: no key, or a key that is unknown, revoked or expired.' headers: Cache-Control: description: no-store on every answer schema: type: string WWW-Authenticate: description: Bearer realm="public-api" schema: type: string X-Request-Id: description: >- this request's id (yours, when you sent X-Request-Id); equals the envelope's request_id schema: type: string '403': content: application/json: schema: $ref: '#/components/schemas/PublicError' description: >- insufficient_scope: the key lacks the scope this route needs; ip_not_allowed: the request came from an address outside the key's allowlist; tier_required: the key owner's plan does not include API access; access_not_granted: API access is free but granted on request; request it on https://trendlinelabs.ai/developer. headers: Cache-Control: description: no-store on every answer schema: type: string X-Request-Id: description: >- this request's id (yours, when you sent X-Request-Id); equals the envelope's request_id schema: type: string '404': content: application/json: schema: $ref: '#/components/schemas/PublicError' description: >- not_found: no such event, market or key; venue_not_listed: the market has no leg on that venue. headers: Cache-Control: description: no-store on every answer schema: type: string X-RateLimit-Limit: description: >- requests allowed per window for this key; present once the key passed the limiter schema: type: integer X-RateLimit-Remaining: description: >- requests left in this window; present once the key passed the limiter schema: type: integer X-RateLimit-Reset: description: >- seconds until the window resets; present once the key passed the limiter schema: type: integer X-Request-Id: description: >- this request's id (yours, when you sent X-Request-Id); equals the envelope's request_id schema: type: string '410': content: application/json: schema: $ref: '#/components/schemas/PublicError' description: 'market_closed: the market''s leg on that venue no longer trades.' headers: Cache-Control: description: no-store on every answer schema: type: string X-RateLimit-Limit: description: >- requests allowed per window for this key; present once the key passed the limiter schema: type: integer X-RateLimit-Remaining: description: >- requests left in this window; present once the key passed the limiter schema: type: integer X-RateLimit-Reset: description: >- seconds until the window resets; present once the key passed the limiter schema: type: integer X-Request-Id: description: >- this request's id (yours, when you sent X-Request-Id); equals the envelope's request_id schema: type: string '422': content: application/json: schema: $ref: '#/components/schemas/PublicError' description: >- invalid_request: a parameter is missing, unknown, malformed or out of bounds, or a cursor does not match; venue_unsupported: the route does not serve that venue. headers: Cache-Control: description: no-store on every answer schema: type: string X-RateLimit-Limit: description: >- requests allowed per window for this key; present once the key passed the limiter schema: type: integer X-RateLimit-Remaining: description: >- requests left in this window; present once the key passed the limiter schema: type: integer X-RateLimit-Reset: description: >- seconds until the window resets; present once the key passed the limiter schema: type: integer X-Request-Id: description: >- this request's id (yours, when you sent X-Request-Id); equals the envelope's request_id schema: type: string '429': content: application/json: schema: $ref: '#/components/schemas/PublicError' description: >- rate_limited: too many requests, or too many failed authentications; wait Retry-After seconds. headers: Cache-Control: description: no-store on every answer schema: type: string Retry-After: description: seconds to wait before retrying schema: type: integer X-RateLimit-Limit: description: >- requests allowed per window for this key; present once the key passed the limiter schema: type: integer X-RateLimit-Remaining: description: >- requests left in this window; present once the key passed the limiter schema: type: integer X-RateLimit-Reset: description: >- seconds until the window resets; present once the key passed the limiter schema: type: integer X-Request-Id: description: >- this request's id (yours, when you sent X-Request-Id); equals the envelope's request_id schema: type: string '500': content: application/json: schema: $ref: '#/components/schemas/PublicError' description: >- internal_error: an unexpected failure on our side; quote the request id. The body may instead be text/plain with no envelope and no X-RateLimit-* headers when a failure escapes the route's own handling. headers: Cache-Control: description: no-store on every answer schema: type: string X-RateLimit-Limit: description: >- requests allowed per window for this key; present once the key passed the limiter schema: type: integer X-RateLimit-Remaining: description: >- requests left in this window; present once the key passed the limiter schema: type: integer X-RateLimit-Reset: description: >- seconds until the window resets; present once the key passed the limiter schema: type: integer X-Request-Id: description: >- this request's id (yours, when you sent X-Request-Id); equals the envelope's request_id schema: type: string '503': content: application/json: schema: $ref: '#/components/schemas/PublicError' description: >- dependency_unavailable: one of our own stores could not be read; retry later; upstream_unavailable: the data source is unreadable, absent or older than its bound; never an empty 200. headers: Cache-Control: description: no-store on every answer schema: type: string X-RateLimit-Limit: description: >- requests allowed per window for this key; present once the key passed the limiter schema: type: integer X-RateLimit-Remaining: description: >- requests left in this window; present once the key passed the limiter schema: type: integer X-RateLimit-Reset: description: >- seconds until the window resets; present once the key passed the limiter schema: type: integer X-Request-Id: description: >- this request's id (yours, when you sent X-Request-Id); equals the envelope's request_id schema: type: string security: - HTTPBearer: [] x-codeSamples: - label: cURL lang: bash source: > #!/bin/sh # getOrderbook: Get a market's order book on one venue. Needs TRENDLINE_API_KEY; TRENDLINE_API_BASE overrides the base. curl -sS "${TRENDLINE_API_BASE:-https://systems.trendlinelabs.ai}/public/v1/markets/mk-btc-100k-2026/orderbook?venue=kalshi&depth=2" \ -H "Authorization: Bearer $TRENDLINE_API_KEY" - label: Python lang: python source: > """getOrderbook: Get a market's order book on one venue. Needs TRENDLINE_API_KEY; TRENDLINE_API_BASE overrides the base.""" import os import requests BASE = os.environ.get("TRENDLINE_API_BASE", "https://systems.trendlinelabs.ai") KEY = os.environ["TRENDLINE_API_KEY"] r = requests.get(f"{BASE}/public/v1/markets/mk-btc-100k-2026/orderbook", params={"venue": "kalshi", "depth": "2"}, headers={"Authorization": f"Bearer {KEY}"}, timeout=10) r.raise_for_status() print(r.json()) - label: JavaScript lang: javascript source: > // getOrderbook: Get a market's order book on one venue. Needs TRENDLINE_API_KEY; TRENDLINE_API_BASE overrides the base. const BASE = process.env.TRENDLINE_API_BASE ?? "https://systems.trendlinelabs.ai"; const KEY = process.env.TRENDLINE_API_KEY; const r = await fetch(`${BASE}/public/v1/markets/mk-btc-100k-2026/orderbook?venue=kalshi&depth=2`, { headers: { Authorization: `Bearer ${KEY}` } }); console.log(r.status, await r.json()); components: schemas: PublicOrderBook: properties: age_ms: description: now - ts_ms, floored at 0 title: Age Ms type: integer as_of_ms: description: when the book was read, unix milliseconds title: As Of Ms type: integer max_age_s: description: the age bound applied to this venue title: Max Age S type: integer 'no': $ref: '#/components/schemas/PublicBookSide' description: the NO book no_source: description: >- book: the venue's own NO book; derived: 1 - the YES book, approximate on Polymarket, whose YES and NO are two real books enum: - book - derived title: No Source type: string ts_ms: description: the YES book's last change, unix ms title: Ts Ms type: integer universal_id: description: the market universal id title: Universal Id type: string venue: description: the venue this book is from enum: - kalshi - polymarket - limitless - predictfun title: Venue type: string venue_market_id: description: the market's id on this venue title: Venue Market Id type: string 'yes': $ref: '#/components/schemas/PublicBookSide' description: the YES book required: - universal_id - venue - venue_market_id - 'yes' - 'no' - no_source - ts_ms - age_ms - max_age_s - as_of_ms title: PublicOrderBook type: object PublicError: properties: error: $ref: '#/components/schemas/PublicErrorBody' description: the refusal required: - error title: PublicError type: object PublicBookSide: properties: asks: description: best first, price ascending items: $ref: '#/components/schemas/PublicBookLevel' title: Asks type: array bids: description: best first, price descending items: $ref: '#/components/schemas/PublicBookLevel' title: Bids type: array required: - bids - asks title: PublicBookSide type: object PublicErrorBody: properties: code: description: >- a machine-readable code from x-known-codes; a new code may be added, so handle an unknown one by its status title: Code type: string x-known-codes: - access_not_granted - dependency_unavailable - insufficient_scope - internal_error - invalid_request - ip_not_allowed - market_closed - not_found - rate_limited - tier_required - unauthorized - upstream_unavailable - venue_not_listed - venue_unsupported message: description: a human-readable explanation; never parse it title: Message type: string request_id: description: >- this request's id, also sent as the X-Request-Id header; quote it when asking for help title: Request Id type: string required: - code - message - request_id title: PublicErrorBody type: object PublicBookLevel: properties: price: description: 0..1 per YES or NO contract title: Price type: number size: description: contracts title: Size type: number required: - price - size title: PublicBookLevel type: object securitySchemes: HTTPBearer: description: 'Authorization: Bearer tl_live_…' scheme: bearer type: http ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.