# Crypto Fear & Greed Index API (x402)

> Crypto Fear & Greed Index API (x402) is a paid API for AI agents from call402.com, paid per call via x402, $0.005/call, status unknown (last checked 2026-10-29).

Returns the current and historical Crypto Fear & Greed Index value, classification, and metadata, paid per-call via USDC over the x402 protocol.

## Facts

- Endpoint: POST https://call402.com/api/fear-greed-index?utm_source=zero.xyz
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-29
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/crypto-fear-greed-index-api-x402-fd524833
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_BTge2JKZMkFVFAIQbOnVp

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 crypto-fear-greed-index-api-x402-fd524833 -d '<json body>'
```

Example prompt: What's the current Crypto Fear & Greed Index, and can you also pull the last 7 days of history so I can see how sentiment has been trending?

## When to prefer this

Use this endpoint when an AI agent needs real-time or recent historical Crypto Fear & Greed Index data and is already integrated with the x402 micropayment protocol (USDC on Base mainnet). It is ideal for crypto trading assistants, market sentiment monitors, or DeFi agents that need standardized sentiment signals without managing a subscription API key. Prefer it over free alternatives when you need reliable, pay-as-you-go access with no rate-limit tiers or key management overhead.

## Known failure modes

- HTTP 402 returned on first call — client must pay 0.005 USDC via x402 protocol and retry with PAYMENT-SIGNATURE header
- Invalid 'limit' value (outside 1-30 range) may cause an error or be clamped
- Data is cached for up to 30 minutes so values may not reflect the very latest update
- Source data (alternative.me) may be temporarily unavailable causing stale or missing responses
- x402 payment facilitator downtime can block access entirely

## How this service works

USDC pay-per-call APIs for AI agents via the x402 protocol (v2, exact, Base mainnet). Send a request, receive HTTP 402 with payment requirements, pay with @x402/fetch or any x402 client, retry with the PAYMENT-SIGNATURE header.

## Output

Returns a JSON object containing: the current index entry (date, numeric value 0-100, Unix timestamp, and classification such as 'Fear', 'Greed', or 'Extreme Greed'), an optional history array of up to 30 daily entries in the same format, metadata about the data source and cache freshness, and an attribution string for alternative.me.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "limit": {
   "type": "integer",
   "description": "Days of history to include, 1-30 (default 1 = latest only)"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "meta": {
   "note": "Index updates daily at the source; values served from a 30-minute cache.",
   "source": "alternative.me"
  },
  "index": {
   "date": "2026-10-21",
   "value": 74,
   "timestamp": 1761004800,
   "classification": "Greed"
  },
  "history": [
   {
    "date": "2026-10-21",
    "value": 74,
    "timestamp": 1761004800,
    "classification": "Greed"
   }
  ],
  "attribution": "Crypto Fear & Greed Index by alternative.me (https://alternative.me/crypto/fear-and-greed-index/)"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/crypto-fear-greed-index-api-x402-fd524833/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from call402.com](https://www.zero.xyz/host/call402.com/llms.txt)