> ## Documentation Index
> Fetch the complete documentation index at: https://docs.polynode.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# Open Interest History

> Open-interest time series — a polynode-exclusive dataset the exchange does not offer.

Open interest is normally only visible as a live number on the [ticker](/perps/market-data/tickers). This endpoint gives you its history:

```bash theme={null}
curl "https://api.polynode.dev/v3/perps/oi/btc?after=1783500000&limit=100&key=$POLYNODE_API_KEY"
```

```json theme={null}
{
  "instrument_id": 6,
  "symbol": "BTC-USD",
  "data": [
    {
      "timestamp": 1783571000000,
      "open_interest": "67.44542",
      "mark_price": "62010",
      "funding_rate": "0.0000125"
    }
  ],
  "more": true
}
```

Each sample carries the mark price and funding rate at that moment, so OI-vs-price studies need no joins. Samples are minute-resolution, newest first.

| Parameter          | Description                           |
| ------------------ | ------------------------------------- |
| `after` / `before` | Time window (Unix seconds or ms)      |
| `limit`            | Max samples (default 500, up to 5000) |

The series accrues from July 9, 2026 onward.