ToolVet
80trust / 100

Arb Same Outcome Spread

by api.seerium.xyz in Markets & finance

x402 APIPassing, checked 3 h ago

Prediction market arbitrage and same-outcome spread API for Polymarket, Kalshi, and Gemini. Finds YES or NO price gaps across venues.

GET https://api.seerium.xyz/v1/prediction/arb/same-outcome-spread

Last 30 days

All checks passedSome failedAll failedNot checked

Status and outage history · Atom feed

Uptime
100%
Response time
214 ms typical, 347 ms slowest 5%
Last check
3 h ago
Next check
any minute now

How to call it

GET https://api.seerium.xyz/v1/prediction/arb/same-outcome-spread

Each call costs $0.1 in USDC on Base, paid with the request over x402.

Run a free test callOne unpaid request, the way an agent sends it. You see the payment challenge it gets back. Nothing is charged.

Example request

From the listing.

GET https://api.seerium.xyz/v1/prediction/arb/same-outcome-spread?includeIndicative=true&limit=3&minEdge=0&sources=polymarket%2Ckalshi%2Cgemini

Parameters

ParameterTypeRequiredDescription
includeIndicativebooleanNoOptional flag for indicative price-only rows. Defaults to true.
limitnumberNoOptional maximum arb rows to return. Defaults to 20 and is hard-capped at 20.
minEdgenumberNoOptional minimum net arb edge as a decimal or percentage-style value.
outcomestringNoOptional same-outcome filter. One of: yes, no.
sourcesstringNoOptional comma-separated venue filter: polymarket, kalshi, gemini.

Example response

The provider's example. We can't check it without paying.

Example response, 169 lines
{
  "data": {
    "criteria": {
      "includeIndicative": true,
      "limit": 20,
      "minEdge": null,
      "outcome": "yes",
      "sources": [],
      "strategy": "same_outcome_spread"
    },
    "markets": 1200,
    "returned": 1,
    "rows": [
      {
        "buy": {
          "conditionId": "GEMEXAMPLE",
          "endDateIso": "2026-03-30T00:00:00.000Z",
          "eventTicker": null,
          "eventTitle": "Example Event",
          "indicative": true,
          "marketSlug": "GEMEXAMPLE",
          "marketTicker": null,
          "marketUrl": "https://polymarket.com/market/example-market",
          "outcome": "yes",
          "price": 0.42,
          "priceType": "ask",
          "question": "Will example event happen by Friday?",
          "seriesTicker": null,
          "side": "BUY",
          "size": null,
          "source": "gemini",
          "tokenId": "GEMEXAMPLE:YES",
          "totalDepth": null
        },
        "edge": 0.035,
        "feeBuffer": 0.002,
        "grossEdge": 0.037,
        "id": "arb_same_outcome_example",
        "key": "question:will example event happen by friday:date:2026-03-30",
        "legs": [
          {
            "conditionId": "GEMEXAMPLE",
            "endDateIso": "2026-03-30T00:00:00.000Z",
            "eventTicker": null,
            "eventTitle": "Example Event",
            "indicative": true,
            "marketSlug": "GEMEXAMPLE",
            "marketTicker": null,
            "marketUrl": "https://polymarket.com/market/example-market",
            "outcome": "yes",
            "price": 0.42,
            "priceType": "ask",
            "question": "Will example event happen by Friday?",
            "seriesTicker": null,
            "side": "BUY",
            "size": null,
            "source": "gemini",
            "tokenId": "GEMEXAMPLE:YES",
            "totalDepth": null
          },
          {
            "conditionId": "0xexample",
            "endDateIso": "2026-03-30T00:00:00.000Z",
            "eventTicker": null,
            "eventTitle": "Example Event",
            "indicative": true,
            "marketSlug": "example-market",
            "marketTicker": null,
            "marketUrl": "https://polymarket.com/market/example-market",
            "outcome": "yes",
            "price": 0.457,
            "priceType": "bid",
            "question": "Will example event happen by Friday?",
            "seriesTicker": null,
            "side": "SELL",
            "size": null,
            "source": "polymarket",
            "tokenId": "poly_yes_token",
            "totalDepth": null
          }
        ],
        "matchedOn": {
          "dateKey": "2026-03-30",
          "directionKey": null,
          "eventKey": "example event",
          "numericKey": null,
          "subjectKey": "will example event happen by friday"
        },
        "outcome": "yes",
        "question": "Will example event happen by Friday?",
        "requiresShort": true,
        "sell": {
          "conditionId": "0xexample",
          "endDateIso": "2026-03-30T00:00:00.000Z",
          "eventTicker": null,
          "eventTitle": "Example Event",
          "indicative": true,
          "marketSlug": "example-market",
          "marketTicker": null,
          "marketUrl": "https://polymarket.com/market/example-market",
          "outcome": "yes",
          "price": 0.457,
          "priceType": "bid",
          "question": "Will example event happen by Friday?",
          "seriesTicker": null,
          "side": "SELL",
          "size": null,
          "source": "polymarket",
          "tokenId": "poly_yes_token",
          "totalDepth": null
        },
        "sources": [
          "gemini",
          "polymarket"
        ],
        "spread": 0.037,
        "strategy": "same_outcome_spread"
      }
    ],
    "sourceTimestamps": {
      "gemini": 1760000000000,
      "kalshi": 1760000000000,
      "polymarket": 1760000000000
    },
    "totalCandidates": 1,
    "totals": {
      "fullCover": 0,
      "gemini": 250,
      "groups": 80,
      "kalshi": 450,
      "polymarket": 500,
      "sameOutcomeSpread": 1
    },
    "updatedAt": "2026-03-25T11:59:30.000Z",
    "warnings": []
  },
  "meta": {
    "freshnessMs": 30000,
    "generatedAt": "2026-03-25T12:00:00.000Z",
    "requestId": "req_example_123",
    "updatedAt": "2026-03-25T11:59:30.000Z"
  },
  "product": {
    "accepts": [
      {
        "network": "eip155:8453",
        "payTo": "0x81832eEDe3a4ad96CB3D7cA09977636D912fd3D5",
        "price": "$0.1000",
        "scheme": "exact"
      },
      {
        "network": "solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp",
        "payTo": "2h752kAbb9z1jpdSzqMEYg9JHv6TPJ6T2BfAJMyjLFtZ",
        "price": "$0.1000",
        "scheme": "exact"
      }
    ],
    "id": "prediction-arb-same-outcome-spread",
    "method": "GET",
    "name": "Prediction Market Same Outcome Spread",
    "networks": [
      "eip155:8453",
      "solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp"
    ],
    "path": "/v1/prediction/arb/same-outcome-spread",
    "price": "$0.1000"
  },
  "service": "seerium-x402-api"
}

Call it from code

The curl command shows the payment challenge. The JavaScript and Python versions pay and call, and never pay more than $0.1.

curl: see the payment challenge
# bash or zsh: see the payment challenge. Nothing is charged.
curl -sS -g -i 'https://api.seerium.xyz/v1/prediction/arb/same-outcome-spread?includeIndicative=true&limit=3&minEdge=0&sources=polymarket%2Ckalshi%2Cgemini'

# x402 v2 sends the challenge base64-encoded in the PAYMENT-REQUIRED header (v1 sends it in the body).
# To read the header:
curl -sS -g -o /dev/null -D - 'https://api.seerium.xyz/v1/prediction/arb/same-outcome-spread?includeIndicative=true&limit=3&minEdge=0&sources=polymarket%2Ckalshi%2Cgemini' \
  | grep -i '^payment-required:' | cut -d' ' -f2 | tr -d '\r' | base64 --decode
JavaScript: pay and call
// npm i @x402/fetch @x402/evm viem
import { wrapFetchWithPayment, x402Client } from "@x402/fetch";
import { registerExactEvmScheme } from "@x402/evm/exact/client";
import { privateKeyToAccount } from "viem/accounts";

// Pays at most $0.1 per call.
const client = new x402Client().setSpendControls({ maxAmountPerPayment: "$0.1" });
registerExactEvmScheme(client, { signer: privateKeyToAccount(process.env.EVM_PRIVATE_KEY) });
const pay = wrapFetchWithPayment(fetch, client);

// Not sure it's safe to pay? ToolVet checks it first for $0.005. Pay for that from a separate
// client: this one is capped at $0.1 per payment. GET https://toolvet.app/api/v1/check?url=https%3A%2F%2Fapi.seerium.xyz%2Fv1%2Fprediction%2Farb%2Fsame-outcome-spread
const res = await pay("https://api.seerium.xyz/v1/prediction/arb/same-outcome-spread?includeIndicative=true&limit=3&minEdge=0&sources=polymarket%2Ckalshi%2Cgemini");
console.log(res.status, await res.text());
Python: pay and call
# pip install "x402[requests,evm]"
import os
from eth_account import Account
from x402 import x402ClientSync
from x402.http.clients import x402_requests
from x402.mechanisms.evm import EthAccountSigner
from x402.mechanisms.evm.exact.register import register_exact_evm_client

# Pays at most $0.1 per call.
client = x402ClientSync().set_spend_controls({"max_amount_per_payment": "$0.1"})
register_exact_evm_client(client, EthAccountSigner(Account.from_key(os.environ["EVM_PRIVATE_KEY"])))

with x402_requests(client) as session:
    res = session.get("https://api.seerium.xyz/v1/prediction/arb/same-outcome-spread?includeIndicative=true&limit=3&minEdge=0&sources=polymarket%2Ckalshi%2Cgemini")
    print(res.status_code, res.text)

Security scan

  • No findings. We scan names, descriptions and tool definitions for hidden instructions and other prompt-injection patterns.

Recent checks

WhenResultHTTPTimePrice
3 h agoPassed402351 ms$0.1
7 h agoPassed402205 ms$0.1
11 h agoPassed402258 ms$0.1
15 h agoPassed402211 ms$0.1
19 h agoPassed402347 ms$0.1
23 h agoPassed402233 ms$0.1
26 h agoPassed402167 ms$0.1
30 h agoPassed402222 ms$0.1
33 h agoPassed402221 ms$0.1
37 h agoPassed402239 ms$0.1
40 h agoPassed402291 ms$0.1
44 h agoPassed402155 ms$0.1
47 h agoPassed402264 ms$0.1
2 days agoPassed402190 ms$0.1
2 days agoPassed402151 ms$0.1