# Polymarket Historical Price / Probability API

> Polymarket Historical Price / Probability API is a paid API for AI agents from api.vextorium.com, paid per call via x402, $0.004/call, status unknown (last checked 2026-10-13).

Returns historical probability time series for a Polymarket prediction market outcome, including max, min, current, and change in percentage points over a chosen interval.

## Facts

- Endpoint: POST https://api.vextorium.com/polymarket-historial-pago?utm_source=zero.xyz
- Price: $0.004/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-13
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/polymarket-historical-price-probability-api-3d5478ca
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_vYvr-e_pDARTwQWDzB4Yb

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-historical-price-probability-api-3d5478ca -d '<json body>'
```

Example prompt: What has the probability of 'Yes' on the Polymarket market 'will-oprah-winfrey-win-the-2028-democratic-presidential-nomination' looked like over the last week? Give me the max, min, and how many percentage points it changed.

## When to prefer this

Use this endpoint when you need historical probability movement data for a specific Polymarket prediction market outcome, particularly when you need max/min/change statistics over a defined time window. Prefer this over generic crypto or financial data APIs when the query is specifically about Polymarket prediction market probabilities.

## Known failure modes

- Invalid or unknown market slug returns null or error response
- Invalid outcome index returns null data
- Network or upstream Polymarket API unavailability
- Market not found or delisted market returns empty series
- Invalid interval enum value rejected by schema validation

## How this service works

How the probability of a Polymarket outcome moved over the last hour, day, week, month or all time, with max, min and change in percentage points.

## Output

A JSON object containing: the full probability time series (array of timestamps with probability_pct values), the market question text, the outcome label, the chosen interval, current probability percentage, max and min probability percentages, and the change in percentage points over the interval.

## 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": {
     "required": [
      "slug"
     ],
     "properties": {
      "slug": {
       "type": "string"
      },
      "intervalo": {
       "enum": [
        "1h",
        "6h",
        "1d",
        "1w",
        "1m",
        "max"
       ],
       "type": "string"
      },
      "resultado": {
       "type": "integer",
       "description": "Outcome index (0 = first)"
      }
     }
    },
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "POST"
     ],
     "type": "string"
    },
    "bodyType": {
     "enum": [
      "json",
      "form-data",
      "text"
     ],
     "type": "string"
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": [
      "object",
      "null"
     ],
     "properties": {
      "serie": {
       "type": [
        "array",
        "null"
       ],
       "items": {
        "type": [
         "null",
         "object"
        ],
        "properties": {
         "fecha": {
          "type": [
           "null",
           "string"
          ]
         },
         "probabilidad_pct": {
          "type": [
           "null",
           "number"
          ]
         }
        }
       }
      },
      "pregunta": {
       "type": [
        "string",
        "null"
       ]
      },
      "cambio_pp": {
       "type": [
        "number",
        "null"
       ]
      },
      "intervalo": {
       "type": [
        "string",
        "null"
       ]
      },
      "resultado": {
       "type": [
        "string",
        "null"
       ]
      },
      "maximo_pct": {
       "type": [
        "number",
        "null"
       ]
      },
      "minimo_pct": {
       "type": [
        "number",
        "null"
       ]
      },
      "probabilidad_actual_pct": {
       "type": [
        "number",
        "null"
       ]
      }
     }
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "serie": [
   {
    "fecha": "2026-10-01T20:30+00:00",
    "probabilidad_pct": 0.05
   },
   {
    "fecha": "2026-10-01T21:00+00:00",
    "probabilidad_pct": 0.05
   }
  ],
  "pregunta": "Will Oprah Winfrey win the 2028 Democratic presidential nomination?",
  "cambio_pp": 0,
  "intervalo": "1d",
  "resultado": "Yes",
  "maximo_pct": 0.05,
  "minimo_pct": 0.05,
  "probabilidad_actual_pct": 0.05
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/polymarket-historical-price-probability-api-3d5478ca/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.vextorium.com](https://www.zero.xyz/host/api.vextorium.com/llms.txt)