# Polymarket Bid-Ask Spread

> Polymarket Bid-Ask Spread is a paid API for AI agents from proxy.suverse.io, paid per call via x402, $0.05/call, status unknown (last checked 2026-09-14).

Returns the current bid-ask spread for a specific Polymarket outcome token from the live CLOB order book, serving as a liquidity and uncertainty gauge.

## Facts

- Endpoint: POST https://proxy.suverse.io/v1/data/polymarket-bid-ask-spread
- Price: $0.05/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/polymarket-bid-ask-spread-144af68a
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_vAwZ8TtSLXaEatNKgZfSC

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability polymarket-bid-ask-spread-144af68a -d '<json body>'
```

Example prompt: What's the current bid-ask spread on Polymarket for the outcome token with ID 0x1234abcd? I want to see how liquid that market is right now.

## When to prefer this

Choose this endpoint when you need real-time bid-ask spread data specifically from Polymarket's CLOB for a known outcome token ID. It is ideal for pre-trade analysis, liquidity screening, or uncertainty measurement on prediction market positions. Prefer this over general market data APIs when working within the Polymarket ecosystem and you already have the token_id from a market detail lookup.

## Known failure modes

- Invalid or unknown token_id returns an error or empty order book
- Token with no active orders returns null bid or ask
- Network latency may cause slightly stale order book snapshots
- Malformed request body returns a 400-level error
- Payment failure (x402) if USDC balance is insufficient

## How this service works

Current bid-ask spread for a Polymarket outcome token from the live order book - a liquidity/uncertainty gauge. Free Polymarket CLOB data. token_id from market detail.

## Output

Returns the current best bid price, best ask price, and the calculated bid-ask spread (ask minus bid) for the specified Polymarket outcome token from the live Central Limit Order Book. A narrow spread indicates high liquidity and market confidence; a wide spread indicates thin liquidity or high uncertainty.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method",
    "bodyType",
    "body"
   ],
   "properties": {
    "body": {
     "properties": {}
    },
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "POST",
      "PUT",
      "PATCH"
     ],
     "type": "string"
    },
    "bodyType": {
     "enum": [
      "json",
      "form-data",
      "text"
     ],
     "type": "string"
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/polymarket-bid-ask-spread-144af68a/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from proxy.suverse.io](https://www.zero.xyz/host/proxy.suverse.io/llms.txt)