Serverless Forecasting Engine

Welcome to weatherman! A free API to forecast your time series

ForecastingAPI.com turns compact JSON payloads into production-grade forecasts, rolling backtests, SMAPE accuracy reports, and shareable run pages — all in one flow.

Start forecasting What is M5 and why it matters?

1) Ingest

Paste one payload with multi-series data. Keep it compact and deterministic.

2) Evaluate

Run rolling backtests with AutoARIMA + AutoETS, then compare SMAPE by model/window.

3) Ship

Get a permalinked forecast report with per-series charts and backfill diagnostics.

Enter Payload, get Forecasts

Supply your own payload, or use our M5 demo

Paste JSON Payload below

Payload instructions

⚠️ Time series are assumed to be continuous at your time granularity. If they are not, backfill them before submitting.

Field	Required	Description	Example
`run_name_root`	Yes	Base run name; app prepends PST timestamp	`my-run`
`start_datetime`	Custom	First timestamp in ISO format	`2026-01-01T00:00:00`
`granularity`	Custom	Step size between points	`1d`, `1h`
`horizon`	No	Forecast periods after history	`7`
`model`	No	Engine selector	`nixtla`
`seasonal_period`	No	Season length for ARIMA/ETS	`7`
`n_series`	No	Series count hint (M5 sampling)	`3`
`backtest_windows`	No	Rolling holdout windows for SMAPE	`3`
`series_names`	Custom	Series IDs (`demo_mode_m5` reserved)	`["trend","seasonal","combined"]`
`series`	Custom	Single list or list-of-lists	`[[...],[...],[...]]`

{
  "start_datetime": "2026-01-01T00:00:00",
  "granularity": "1d",
  "horizon": 7,
  "model": "nixtla",
  "seasonal_period": 7,
  "run_name_root": "my-forecast-run",
  "n_series": 3,
  "backtest_windows": 3,
  "series_names": [
    "trend",
    "seasonal",
    "combined"
  ],
  "series": [
    [
      100,
      103,
      101,
      106,
      108,
      107,
      111,
      114,
      113,
      117,
      116,
      120,
      123,
      121,
      126,
      128,
      127,
      131,
      134,
      132,
      137,
      139,
      138,
      142,
      145,
      143,
      148,
      150,
      149,
      153,
      156,
      154,
      159,
      161,
      160,
      164,
      167,
      165,
      170,
      172,
      171,
      175,
      178,
      176,
      181,
      183,
      182,
      186,
      189
    ],
    [
      13,
      18,
      25,
      17,
      9,
      14,
      22,
      12,
      18,
      25,
      17,
      9,
      14,
      22,
      13,
      18,
      25,
      17,
      9,
      14,
      22,
      12,
      18,
      25,
      17,
      9,
      14,
      22,
      13,
      18,
      25,
      17,
      9,
      14,
      22,
      12,
      18,
      25,
      17,
      9,
      14,
      22,
      13,
      18,
      25,
      17,
      9,
      14,
      22
    ],
    [
      114,
      119,
      131,
      121,
      119,
      123,
      136,
      124,
      136,
      142,
      139,
      130,
      140,
      149,
      139,
      150,
      156,
      153,
      143,
      154,
      163,
      152,
      164,
      170,
      167,
      158,
      168,
      177,
      167,
      178,
      184,
      181,
      171,
      182,
      191,
      180,
      192,
      198,
      195,
      186,
      196,
      205,
      195,
      206,
      212,
      209,
      199,
      210,
      219
    ]
  ]
}

All Runs

Most recent forecast outputs available right now.

Welcome to weatherman! A free API to forecast your time series

1) Ingest

2) Evaluate

3) Ship

Enter Payload, get Forecasts

All Runs

20260223-150620-pst-my-forecast-run

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20260223-130110-pst-demo-m5-test

20260223-130106-pst-my-forecast-run

20260223-125244-pst-my-forecast-run

20260223-125102-pst-status-custom-1

20260223-124255-pst-my-forecast-run

20260223-123912-pst-my-forecast-run

20260223-201831-regression-custom

20260223-201040-debug

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20260223-200414-my-forecast-run

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20260223-193801-my-forecast-run

run-fix-test