Developer API & CLI

Quick start

One URL, three formats

The same endpoint serves all three, so you never have to pick a different host for a script:

Response shape

Every JSON response carries a tool field naming the endpoint, so a client can tell what it got. Errors return HTTP 400 with a JSON body too — never an empty response.

{
  "tool": "cron",
  "expression": "*/5 * * * *",
  "human": "At every 5 minutes",
  "nextRuns": [
    {
      "utc": "2026-09-28 14:10:00 UTC",
      "iso": "2026-09-28T14:10:00.000Z",
      "epoch": 1790604600,
      "relative": "in 2m"
    }
  ]
}

What "data" contains

Tool endpoints return their computed result under a data key: the parsed cron expression with its next runs, the current time in every supported zone with DST state, the reference tables behind the format pages, and so on. The same values are what the browser draws, so a script and a person always see the same answer.

A few pages have nothing to compute and return "data": null rather than an empty object: the category hubs, the crontab linter (which needs a POST body), and the Pomodoro timer (which runs in the browser). That is deliberate — a null is a truthful "no structured data for this route", so a client can branch on it instead of parsing an empty result.