# Carbon & Cashmere Rolling Correlation API – BTC-ETH

> Carbon & Cashmere Rolling Correlation API – BTC-ETH is a paid API for AI agents from api.carbon-cashmere.de, paid per call via x402, $0.05/call, status unknown (last checked 2026-09-15).

Returns the rolling 30-day correlation between BTC and ETH, including percentile rank, trend regime, and statistical summary over a 90-day lookback window.

## Facts

- Endpoint: GET https://api.carbon-cashmere.de/v1/rolling-correlation/BTC-ETH
- Price: $0.05/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/carbon-cashmere-rolling-correlation-api-btc-eth-578336a3
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_yu27rUsSTcrhvswe9qn8k

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 carbon-cashmere-rolling-correlation-api-btc-eth-578336a3
```

Example prompt: What's the current rolling 30-day correlation between BTC and ETH, and how does it compare historically — is it in a strongly positive regime right now?

## When to prefer this

Use this endpoint when you need a statistically grounded, regime-labeled rolling correlation between BTC and ETH — especially when you want not just the raw number but its historical percentile context, trend direction, and regime classification (strongly_positive, neutral, etc.). Prefer over generic price APIs when the goal is portfolio diversification analysis, pair trading signals, or risk-on/risk-off regime detection between two major crypto assets.

## Known failure modes

- Invalid or unsupported currency pair returns 404 or empty result
- Missing x402 payment header causes 402 Payment Required response
- Network timeout if upstream price data feed is delayed
- Malformed pair format (e.g. 'BTCETH' instead of 'BTC-ETH') may return 400 or null data
- Insufficient historical data for the requested window returns reduced data_points or error

## How this service works

Professional crypto market intelligence. Real-time prices, signals, and market scoring.

## Output

Returns a JSON object with the current BTC-ETH Pearson correlation (e.g. 0.82), the correlation regime label (e.g. 'strongly_positive'), trend direction (e.g. 'stable'), percentile rank within the 90-day lookback (e.g. 0.68), mean and standard deviation of correlation over the lookback, and the number of data points used (e.g. 540), along with base/quote coin identifiers and a disclaimer.

## Request schema (JSON Schema)

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

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "base": "BTC",
  "pair": "BTC-ETH",
  "_meta": {
   "disclaimer": "Informational research data only — not investment advice."
  },
  "quote": "ETH",
  "trend": "stable",
  "regime": "strongly_positive",
  "statistics": {
   "std_over_lookback": 0.08,
   "current_percentile": 0.68,
   "mean_over_lookback": 0.78
  },
  "data_points": 540,
  "window_days": 30,
  "lookback_days": 90,
  "current_correlation": 0.82
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/carbon-cashmere-rolling-correlation-api-btc-eth-578336a3/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.carbon-cashmere.de](https://www.zero.xyz/host/api.carbon-cashmere.de/llms.txt)