# 2s.io Polymarket–Kalshi Matched Pairs

> 2s.io Polymarket–Kalshi Matched Pairs is a paid API for AI agents from 2s.io, paid per call via x402, $0.012/call, status unknown (last checked 2026-09-15).

Fuzzy-matches open Polymarket and Kalshi prediction markets by title similarity and returns candidate equivalent pairs with YES prices and implied-probability spreads for arbitrage or relative-value analysis.

## Facts

- Endpoint: GET https://2s.io/api/predict/matched-pairs
- Price: $0.012/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/2s-io-polymarket-kalshi-matched-pairs-c75e4fb5
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_ttxxz1Rm2Opmx36Njv60g

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 2s-io-polymarket-kalshi-matched-pairs-c75e4fb5
```

Example prompt: Can you pull the top 10 matched pairs between Polymarket and Kalshi right now — only show me ones with a title-similarity score above 0.6 so I can spot any meaningful YES-price spreads worth investigating?

## When to prefer this

Use this endpoint when you need a live cross-venue view of prediction market pricing discrepancies between Polymarket and Kalshi without building your own fuzzy-matching pipeline. It is keyless and pay-per-call, making it ideal for ad-hoc arbitrage screening or relative-value research. Prefer it over manual comparison when you need ranked candidates quickly with tunable similarity filtering.

## Known failure modes

- No pairs found above requested minScore threshold — returns empty list
- limit out of range (must be 1–50) — returns validation error
- minScore out of range (must be 0–1) — returns validation error
- Markets may have shifted or closed between crawl and response — stale data possible
- High similarity score does not guarantee identical contract terms — heuristic only

## How this service works

Cross-venue equivalent-market pairs for arbitrage / relative-value spotting. We fuzzy-match open Polymarket vs Kalshi markets by title-token overlap and return candidate pairs with both venues' YES prices and the implied-probability spread (Polymarket YES minus Kalshi YES). Tune with minScore (0-1 title-similarity floor) and limit. Heuristic — a high score is a strong candidate, not a guaranteed identical contract. Read-only, keyless. No public source maps these directly; the pairing is derived by 2s.io.

## Output

A list of candidate cross-venue market pairs, each containing the matched Polymarket and Kalshi market titles, their respective YES prices, the implied-probability spread (Polymarket YES minus Kalshi YES), and a title-similarity score. Tunable by minScore and limit.

## 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",
    "queryParams"
   ],
   "properties": {
    "type": {
     "const": "http"
    },
    "method": {
     "const": "GET"
    },
    "queryParams": {
     "type": "object",
     "properties": {
      "limit": {
       "type": "integer",
       "maximum": 50,
       "minimum": 1,
       "description": "Max pairs (default 20)."
      },
      "minScore": {
       "type": "number",
       "maximum": 1,
       "minimum": 0,
       "description": "Minimum title-similarity score 0-1 (default 0.3)."
      }
     },
     "additionalProperties": false
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/2s-io-polymarket-kalshi-matched-pairs-c75e4fb5/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from 2s.io](https://www.zero.xyz/host/2s.io/llms.txt)