# BTC Kalshi-Polymarket Arbitrage Monitor (x402)

> BTC Kalshi-Polymarket Arbitrage Monitor (x402) is a paid API for AI agents from browser-worker-v2-production.up.railway.app, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-19).

Returns matched Kalshi and Polymarket US BTC 15-minute BRTI contract data to surface real-time arbitrage opportunities between the two prediction markets.

## Facts

- Endpoint: GET https://browser-worker-v2-production.up.railway.app/api/btc-kalshi-polymarket-arbitrage?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-19
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/btc-kalshi-polymarket-arbitrage-monitor-x402-c1ead06d
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_xtHhXTbJfZf43Bh0_bs1G

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 btc-kalshi-polymarket-arbitrage-monitor-x402-c1ead06d
```

Example prompt: Pull the latest matched BTC 15-minute BRTI contract prices from both Kalshi and Polymarket and tell me if there's an arbitrage spread worth acting on right now.

## When to prefer this

Use this endpoint when you need real-time, matched BTC 15-minute BRTI contract pricing from both Kalshi and Polymarket in a single call, specifically to identify arbitrage opportunities. Prefer this over scraping each market independently when you need pre-matched contract pairs and want to pay only per call via x402 micropayments rather than managing API subscriptions to both platforms separately.

## Known failure modes

- Payment not received or USDC transaction fails — endpoint returns HTTP 402 and no data
- Kalshi or Polymarket API is down — endpoint may return partial data or an error indicating upstream unavailability
- No matched contracts found for the current 15-minute window — response may be empty or indicate no active matching contracts
- Invalid request_id format — likely echoed as-is but may cause unexpected correlation issues
- Rate limiting or Railway infrastructure outage — HTTP 5xx response

## How this service works

Pay-per-call market-data API for matched Kalshi and Polymarket US BTC 15-minute BRTI contracts. x402 v2, Base mainnet USDC.

## Output

A JSON object containing matched BTC 15-minute BRTI contract data from both Kalshi and Polymarket, including contract prices, implied probabilities or values, spread information, and optionally the echoed requestId for correlation. Enables side-by-side comparison to identify arbitrage opportunities.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "request_id": {
   "type": "string",
   "description": "Optional client correlation identifier, echoed as requestId in the JSON response."
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "object"
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/btc-kalshi-polymarket-arbitrage-monitor-x402-c1ead06d/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from browser-worker-v2-production.up.railway.app](https://www.zero.xyz/host/browser-worker-v2-production.up.railway.app/llms.txt)