# Seerium Same-Outcome Spread / Arbitrage API

> Seerium Same-Outcome Spread / Arbitrage API is a paid API for AI agents from api.seerium.xyz, paid per call via x402, $0.003/call, status unknown (last checked 2026-09-14).

Finds price gaps for the same YES or NO outcome across Polymarket, Kalshi, and Gemini prediction markets to surface arbitrage opportunities.

## Facts

- Endpoint: GET https://api.seerium.xyz/v1/prediction/arb/same-outcome-spread
- Price: $0.003/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/api-seerium-xyz-c452ad0d
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_MKiZbDS4Y0zKdUoIqeSSb

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 api-seerium-xyz-c452ad0d
```

Example prompt: Show me the top 10 same-outcome arbitrage spreads across Polymarket, Kalshi, and Gemini right now — only YES outcomes with at least a 3% edge, and include indicative price rows too.

## When to prefer this

Use this endpoint when you need real-time cross-venue same-outcome spread data specifically across Polymarket, Kalshi, and Gemini. It is the right choice for agents executing or evaluating prediction market arbitrage strategies, as it abstracts multi-venue price comparison into a single ranked feed. Prefer it over building manual per-venue price fetches when you need a clean, filtered, edge-ranked arb signal.

## Known failure modes

- No arb rows found matching the minEdge threshold — returns empty result set
- Invalid outcome enum value (not 'yes' or 'no') causes validation error
- limit exceeds hard cap of 20 — capped silently or returns error
- Unknown venue name in sources filter — may return empty or error
- Payment failure (x402) if USDC balance insufficient — 402 response before data is returned

## How this service works

Crypto and prediction market intelligence through x402.

## Output

A ranked list of arbitrage rows showing same-outcome price gaps across prediction market venues, including the net edge, the venues involved, the outcome side (YES/NO), and optionally indicative-only price entries — up to 20 rows.

## Example request

```json
{
 "input": {
  "type": "http",
  "method": "GET",
  "queryParams": {
   "limit": 10,
   "minEdge": 0.03,
   "outcome": "yes",
   "sources": "polymarket,kalshi,gemini",
   "includeIndicative": true
  }
 }
}
```

## 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"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "properties": {
      "limit": {
       "type": "number",
       "maximum": 20,
       "minimum": 1,
       "description": "Optional maximum arb rows to return. Defaults to 20 and is hard-capped at 20."
      },
      "minEdge": {
       "type": "number",
       "minimum": 0,
       "description": "Optional minimum net arb edge as a decimal or percentage-style value."
      },
      "outcome": {
       "enum": [
        "yes",
        "no"
       ],
       "type": "string",
       "description": "Optional same-outcome filter."
      },
      "sources": {
       "type": "string",
       "description": "Optional comma-separated venue filter: polymarket, kalshi, gemini."
      },
      "includeIndicative": {
       "type": "boolean",
       "description": "Optional flag for indicative price-only rows. Defaults to true."
      }
     },
     "additionalProperties": false
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "data": {
   "rows": [
    {
     "id": "arb_same_outcome_example",
     "buy": {
      "side": "BUY",
      "size": null,
      "price": 0.42,
      "source": "gemini",
      "outcome": "yes",
      "tokenId": "GEMEXAMPLE:YES",
      "question": "Will example event happen by Friday?",
      "marketUrl": "https://polymarket.com/market/example-market",
      "priceType": "ask",
      "endDateIso": "2026-03-30T00:00:00.000Z",
      "eventTitle": "Example Event",
      "indicative": true,
      "marketSlug": "GEMEXAMPLE",
      "totalDepth": null,
      "conditionId": "GEMEXAMPLE",
      "eventTicker": null,
      "marketTicker": null,
      "seriesTicker": null
     },
     "key": "question:will example event happen by friday:date:2026-03-30",
     "edge": 0.035,
     "legs": [
      {
       "side": "BUY",
       "size": null,
       "price": 0.42,
       "source": "gemini",
       "outcome": "yes",
       "tokenId": "GEMEXAMPLE:YES",
       "question": "Will example event happen by Friday?",
       "marketUrl": "https://polymarket.com/market/example-market",
       "priceType": "ask",
       "endDateIso": "2026-03-30T00:00:00.000Z",
       "eventTitle": "Example Event",
       "indicative": true,
       "marketSlug": "GEMEXAMPLE",
       "totalDepth": null,
       "conditionId": "GEMEXAMPLE",
       "eventTicker": null,
       "marketTicker": null,
       "seriesTicker": null
      },
      {
       "side": "SELL",
       "size": null,
       "price": 0.457,
       "source": "polymarket",
       "outcome": "yes",
       "tokenId": "poly_yes_token",
       "question": "Will example event happen by Friday?",
       "marketUrl": "https://polymarket.com/market/example-market",
       "priceType": "bid",
       "endDateIso": "2026-03-30T00:00:00.000Z",
       "eventTitle": "Example Event",
       "indicative": true,
       "marketSlug": "example-market",
       "totalDepth": null,
       "conditionId": "0xexample",
       "eventTicker": null,
       "marketTicker": null,
       "seriesTicker": null
      }
     ],
     "sell": {
      "side": "SELL",
      "size": null,
      "price": 0.457,
      "source": "polymarket",
      "outcome": "yes",
      "tokenId": "poly_yes_token",
      "question": "Will example event happen by Friday?",
      "marketUrl": "https://polymarket.com/market/example-market",
      "priceType": "bid",
      "endDateIso": "2026-03-30T00:00:00.000Z",
      "eventTitle": "Example Event",
      "indicativ
… (truncated)
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/api-seerium-xyz-c452ad0d/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.seerium.xyz](https://www.zero.xyz/host/api.seerium.xyz/llms.txt)