Polymarket vs Kalshi Matched Market: Daily Volume and Open Interest (Last 90 Days)

omnial/polymarket-kalshi-pair-daily-volume-oi-90d

Given a Polymarket condition ID and the Kalshi ticker of the matching market, returns one row per UTC day for the last 90 days, newest first: Polymarket's daily volume and open interest in USD next to Kalshi's daily volume and open interest in contracts. Only the 90-day window is offered. A Kalshi figure of 0 can mean the source has no Kalshi data for that day, not that nothing traded.

activeper callv1

Price

Up to $0.0328 per call; you pay what the call used

The price shown is the price you pay. No monthly minimum. Top-ups start at $5.

Data source

Polymarket and Kalshi

Data from Polymarket and Kalshi.

Use it

Five steps: search, inspect, learn, run, settle. No per-tool setup; your agent reaches this tool through the meta-tools it already has.

agent

// 1. search: find the tool
omnial_search({ query: "what you need" })

// 2. inspect: price and input schema
omnial_inspect({ tool: "omnial/polymarket-kalshi-pair-daily-volume-oi-90d" })

// 3. learn: read the usage guide at runtime
omnial_learn({ tool: "omnial/polymarket-kalshi-pair-daily-volume-oi-90d" })

// 4. run: price the exact call first, then run it
omnial_execute({ tool: "omnial/polymarket-kalshi-pair-daily-volume-oi-90d", input: { /* see input_schema */ }, dry_run: true })
omnial_execute({ tool: "omnial/polymarket-kalshi-pair-daily-volume-oi-90d", input: { /* ... */ } })

// 5. settle: the call is charged when it finishes, nothing to do

Not connected yet? Point your MCP client at https://mcp.eden-engine.com/mcp, then copy a config for your client.

Pricing

Every charge this tool can incur.

Charge	Price
Per call	$0.0328

Updated: Oct 14, 2026

Input and output schemas

Input schema

input_schema.json

{
  "type": "object",
  "required": [
    "polymarket_condition_id",
    "kalshi_market_ticker",
    "time_range"
  ],
  "properties": {
    "limit": {
      "enum": [
        200
      ],
      "type": "integer",
      "description": "Maximum rows; only 200 is offered, which covers the 90 daily rows."
    },
    "offset": {
      "enum": [
        0
      ],
      "type": "integer",
      "description": "Rows to skip; only 0 is offered (no paging)."
    },
    "time_range": {
      "enum": [
        "90d"
      ],
      "type": "string",
      "description": "The window of history; only \"90d\" (the last 90 days) is offered."
    },
    "kalshi_market_ticker": {
      "type": "string",
      "minLength": 1,
      "description": "The ticker of the matching Kalshi market, as Kalshi shows it."
    },
    "polymarket_condition_id": {
      "type": "string",
      "pattern": "^0x[0-9a-fA-F]{64}$",
      "description": "The Polymarket market's condition ID, a 0x-prefixed 64-digit hex string."
    }
  },
  "additionalProperties": false
}

Output schema

output_schema.json

{
  "type": "object",
  "properties": {
    "data": {
      "type": "array",
      "items": {
        "type": "object",
        "properties": {
          "timestamp": {
            "type": "number",
            "description": "The start of the day, a Unix timestamp in seconds (00:00 UTC)."
          },
          "polymarket_oi_usd": {
            "type": "number",
            "description": "The Polymarket market's open interest that day, USD."
          },
          "kalshi_oi_contracts": {
            "type": "number",
            "description": "The Kalshi market's open interest that day, in contracts (can be fractional); 0 can mean no Kalshi data for the day."
          },
          "polymarket_volume_usd": {
            "type": "number",
            "description": "The Polymarket market's trading volume that day, USD."
          },
          "kalshi_volume_contracts": {
            "type": "number",
            "description": "The Kalshi market's trading volume that day, in contracts; 0 can mean no Kalshi data for the day."
          }
        }
      },
      "description": "One row per UTC day, newest first."
    }
  },
  "description": "The matched pair's daily series."
}