ARIMA / SARIMA Web App v2

Browser frontend connected to a FastAPI backend for time-series exploration, conditional least-squares estimation, simulation forecasting, diagnostics, and Excel export.

Signal after plot preprocessing
Spectrum
ACF / PACF
Forecast paths / one-step-ahead comparison
Forecast interval / forecast-vs-actual scatter

This browser implementation uses conditional least squares with iterative residual regression. It does not reproduce MATLAB Econometrics Toolbox maximum-likelihood estimation exactly.