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Bookproof — Polymarket Market Health & Order Book Intelligence
x402
Bookproof — Polymarket Market Health & Order Book Intelligence is a paid API for AI agents from bookproof-api.sn95wjq846.chatgpt.site, paid per call via x402, $0.005/call, status unknown (last checked 2026-09-14).
Returns real-time Polymarket order book depth, spread, fees, freshness, and executable VWAP data for a given prediction market.
Price / call$0.005
Success—
StatusUnknown
How this service works
Read-only Polymarket depth, spread, fee, freshness, and executable VWAP data for autonomous agents, paid per call with x402.
Output
Returns a JSON object containing: the market slug, per-outcome order book data (best bid, best ask, spread, 2-cent imbalance), fee parameters (taker rate, exponent, taker-only flag), and a health object indicating whether the book is stale, crossed, or healthy.
Example use cases
Pre-trade liquidity check for prediction market
“Before I trade on Polymarket, check the order book for the 'will-trump-win-the-2026-midterms' market — I need to know the best bid and ask, the spread, whether the book is healthy, and what taker fees I'll be charged.”
Automated trading bot market health monitor
“Every minute, pull the market health and spread data for Polymarket's 'will-btc-hit-100k-by-end-of-2025' market and alert me if the book goes stale, crossed, or if the spread widens beyond 3 cents.”
Fee-aware execution cost estimation
“I'm about to execute a large trade on Polymarket — can you pull the current order book imbalance, VWAP, and taker fee rate for the 'will-the-fed-decrease-interest-rates-by-25-bps-after-the-july-2026-meeting' market so I can estimate my total execution cost?”
Technical details
Endpoint
GEThttps://bookproof-api.sn95wjq846.chatgpt.site/api/v1/market-healthWhen to prefer
Use this endpoint when an autonomous agent needs pre-trade intelligence on Polymarket — specifically when fee-aware execution cost, spread, order book freshness, and health checks are required before placing or sizing a trade. Prefer this over generic Polymarket API calls when you need VWAP, imbalance, and fee data in a single response, or when you need to verify that the book is not crossed or stale before committing capital.
Side effects
- Market not found: invalid slug, URL, or token ID returns an error or empty result
- Stale data: health.stale=true indicates the order book hasn't been updated recently
- Crossed book: health.crossed=true means best bid >= best ask, making execution unreliable
- Payment failure: missing or invalid x402 payment header results in 402 response
- Rate limiting: excessive calls without valid payment may be throttled
- Ambiguous search phrase: non-unique market search phrase may resolve to wrong market
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Output
Schema · Response
{
"type": "json",
"example": {
"fee": {
"exponent": 1,
"takerOnly": true,
"takerRate": 0.04
},
"books": [
{
"spread": 0.01,
"bestAsk": 0.43,
"bestBid": 0.42,
"outcome": "Yes",
"imbalance2c": -0.12
}
],
"health": {
"stale": false,
"status": "healthy",
"crossed": false
},
"market": {
"slug": "will-the-fed-decrease-interest-rates-by-25-bps-after-the-july-2026-meeting"
},
"service": "bookproof"
}
}Tags
x402
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