# HARS-Zero Signal API – Alpha Feed

> HARS-Zero Signal API – Alpha Feed is a paid API for AI agents from hars.cryptotavern.xyz, paid per call via x402, $0.8/call, status unknown (last checked 2026-09-15).

Returns Polymarket prediction-market intelligence data (active markets, signals) for AI agents, gated by pay-per-call USDC payment via x402 protocol.

## Facts

- Endpoint: GET https://hars.cryptotavern.xyz/paid/premium/alpha-feed
- Price: $0.8/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/hars-zero-signal-api-alpha-feed-ab530620
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_AhfIq9VakFw_NmNC4mZkU

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 hars-zero-signal-api-alpha-feed-ab530620
```

Example prompt: Pull the latest alpha feed from HARS-Zero and show me which Polymarket prediction markets are currently most active — I want to see what markets are available right now.

## When to prefer this

Choose this endpoint when an AI agent needs real-time Polymarket prediction-market intelligence and is capable of paying per-call in USDC via the x402 protocol. Prefer it over free alternatives when premium alpha signals are needed for automated trading or decision-making agents operating on Base or Solana chains.

## Known failure modes

- 402 Payment Required – x402 payment not included or insufficient USDC balance
- Empty markets array – no markets match the provided filter properties
- Invalid property filter schema – malformed input properties object
- Network timeout – upstream Polymarket data unavailable
- Rate limiting – too many calls in a short window

## How this service works

Polymarket prediction-market intelligence for AI agents. Pay-per-call in USDC via x402 protocol. Multi-chain: Base + Solana.

## Output

Returns a JSON object containing a count of matching markets and an array of market objects from the Polymarket prediction platform. Each market entry includes signal and intelligence data relevant to AI agent decision-making. Empty arrays indicate no matching markets for the given filter.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "properties": {
   "type": "string"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "object",
 "example": {
  "count": 0,
  "markets": []
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/hars-zero-signal-api-alpha-feed-ab530620/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from hars.cryptotavern.xyz](https://www.zero.xyz/host/hars.cryptotavern.xyz/llms.txt)