# Polymarket Open Interest Lookup

> Polymarket Open Interest Lookup is a paid API for AI agents from AIsa MPP Data APIs at api.aisa.one, paid per call via MPP, $0.00044/call, status unknown (last checked 2026-10-18).

Retrieves open interest values for one or more Polymarket prediction markets by their market IDs.

## Facts

- Endpoint: GET https://api.aisa.one/apis/v1/polymarket/oi?utm_source=zero.xyz
- Price: $0.00044/call
- Payment: MPP
- Status: unknown
- Last checked: 2026-10-18
- Activations on Zero: 0
- Provider: AIsa MPP Data APIs
- Website: https://aisa.one
- Tags: web-search, financial-data, prediction-markets, weather, travel, data, search
- Canonical page: https://www.zero.xyz/c/aisa-mpp-data-apis-polymarket-open-interest-lookup-de3d8ca2
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap__qBE3zi1Q3lGw4REtJVvm

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 aisa-mpp-data-apis-polymarket-open-interest-lookup-de3d8ca2
```

Example prompt: What's the current open interest on the Polymarket market 0xdd22472e552920b8438158ea7238bfadfa4f736aa4cee91a6b86c39ead110917?

## When to prefer this

Use this endpoint when you need open interest data specifically from Polymarket prediction markets, identified by their 0x-prefixed market contract addresses. It supports batch queries for multiple markets in a single call, making it efficient for comparing OI across markets. Prefer this over general market data APIs when you need Polymarket-specific OI figures for trading analysis, liquidity assessment, or monitoring.

## Known failure modes

- Invalid market ID format (not a 0x-prefixed 64-hex string) returns a validation error
- Market ID not found on Polymarket returns no data or zero value
- Empty market array or missing parameter returns an empty array
- Network or upstream Polymarket API unavailability causes request failure

## How this service works

Get open interest for one or more markets.

<!-- aisa-pricing:start -->
Published reference price: $0.00044 USD per successful request. Account-specific pricing and final settlement may differ.
<!-- aisa-pricing:end -->

## Output

Returns an array of objects, each containing a market ID (0x-prefixed 64-hex string) and its corresponding open interest value as a number. If multiple market IDs are queried, one object is returned per market.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "market": {
   "type": "array",
   "items": {
    "type": "string",
    "example": "0xdd22472e552920b8438158ea7238bfadfa4f736aa4cee91a6b86c39ead110917",
    "pattern": "^0x[a-fA-F0-9]{64}$",
    "description": "0x-prefixed 64-hex string"
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "array",
 "items": {
  "type": "object",
  "properties": {
   "value": {
    "type": "number"
   },
   "market": {
    "type": "string",
    "example": "0xdd22472e552920b8438158ea7238bfadfa4f736aa4cee91a6b86c39ead110917",
    "pattern": "^0x[a-fA-F0-9]{64}$",
    "description": "0x-prefixed 64-hex string"
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/aisa-mpp-data-apis-polymarket-open-interest-lookup-de3d8ca2/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.aisa.one](https://www.zero.xyz/host/api.aisa.one/llms.txt)