# Time Series Calculators

Moving averages, exponential smoothing, autocorrelation, outliers, decomposition, growth rates, change points and forecast accuracy for a list of numbers.

## How to pay

Machine-payable over x402. USDC on: Base (eip155:8453), Solana (solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp), Polygon (eip155:137), Arbitrum One (eip155:42161).
No accounts. No API keys. No signup. The paying wallet is the account.

## Machine-readable

- OpenAPI: https://time-series-calc.x402tookit.com/openapi.json
- x402 manifest: https://time-series-calc.x402tookit.com/.well-known/x402
- Catalog (free): https://time-series-calc.x402tookit.com/catalog
- Health (free): https://time-series-calc.x402tookit.com/health
- Uptime (free): https://time-series-calc.x402tookit.com/uptime

## Endpoints (8)

### GET /autocorrelation — $0.02
Sample autocorrelation (ACF) and partial autocorrelation (PACF, Durbin-Levinson) of a series up to lag k, with 95% bounds.
Params: values: string, maxLag?: integer
Example: https://time-series-calc.x402tookit.com/autocorrelation?values=1%2C2%2C3%2C4%2C5&maxLag=2

### GET /change-points — $0.03
Find level shifts in a series with two-sided CUSUM alarms and a mean-shift binary segmentation, positions 1-based.
Params: values: string, method?: string, target?: number, sigma?: number, k?: number, h?: number, maxChanges?: integer, minSegment?: integer
Example: https://time-series-calc.x402tookit.com/change-points?values=1%2C1%2C1%2C1%2C1%2C5%2C5%2C5%2C5%2C5&method=binseg

### GET /exponential-smoothing — $0.03
Simple, Holt trend or Holt-Winters seasonal exponential smoothing with a forecast h steps ahead and in-sample fit error.
Params: values: string, method?: string, alpha?: number, beta?: number, gamma?: number, seasonLength?: integer, horizon?: integer
Example: https://time-series-calc.x402tookit.com/exponential-smoothing?values=10%2C12%2C11%2C13%2C15%2C14%2C16%2C18&method=holt&alpha=0.5&beta=0.3&horizon=3

### GET /forecast-accuracy — $0.02
Score a forecast against actuals: MAE, RMSE, MAPE, sMAPE, bias and MASE against a naive benchmark.
Params: actual: string, forecast: string, training?: string, seasonLength?: integer
Example: https://time-series-calc.x402tookit.com/forecast-accuracy?actual=3%2C5%2C2%2C7&forecast=2%2C5%2C4%2C8&training=1%2C3%2C2%2C5%2C4

### GET /growth-rates — $0.02
Period-over-period percent change, log returns, CAGR and rolling growth for a list of values in time order.
Params: values: string, periodsPerYear?: number, rollingWindow?: integer
Example: https://time-series-calc.x402tookit.com/growth-rates?values=100%2C110%2C121%2C133.1&periodsPerYear=1&rollingWindow=2

### GET /moving-average — $0.02
Simple, exponential or weighted moving average of a list of numbers, trailing or centered, with the alignment stated.
Params: values: string, type?: string, window?: integer, alpha?: number, span?: integer, align?: string, weights?: string
Example: https://time-series-calc.x402tookit.com/moving-average?values=10%2C12%2C11%2C13%2C15%2C14%2C16&type=sma&window=3

### GET /outliers — $0.02
Flag outliers in a list of numbers by z-score, Tukey IQR fences and the MAD modified z-score (3.5 rule).
Params: values: string, method?: string, zLimit?: number, iqrMultiplier?: number, madLimit?: number
Example: https://time-series-calc.x402tookit.com/outliers?values=1%2C2%2C3%2C4%2C5%2C6%2C7%2C8%2C9%2C100

### GET /trend-seasonality — $0.03
Classical additive decomposition of a series into trend, seasonal and remainder parts for a given period.
Params: values: string, period: integer
Example: https://time-series-calc.x402tookit.com/trend-seasonality?values=12%2C11%2C15%2C12%2C16%2C15%2C19%2C16%2C20%2C19%2C23%2C20&period=4

## Terms

Time series arithmetic computed locally from the numbers given, using standard textbook formulas, provided as is. Smoothing, forecasts and change points are descriptive statistics on your data, not predictions you can rely on, and not financial, investment or business advice.