explain-cron

Explain any cron expression in plain English. Show the next 10 run times. Zero config.

$ npx explain-cron "*/5 * * * *"

Expression: */5 * * * *
Meaning:    Every 5 minutes

Next 10 run times (local time):
   1. Mon, May 18, 2026, 23:20 MDT
   2. Mon, May 18, 2026, 23:25 MDT
   3. Mon, May 18, 2026, 23:30 MDT
   ...

Install

Run it on the fly:

npx explain-cron "0 9 * * 1-5"

Or install globally:

npm install -g explain-cron
explain-cron "@daily"

Requires Node.js 18 or newer.

Usage

explain-cron "<cron expression>" [--count N] [--tz <IANA-tz>]
explain-cron --pro
explain-cron --help
explain-cron --version

Examples:

explain-cron "*/15 * * * *"
explain-cron "0 9 * * 1-5"                    # weekdays at 9am
explain-cron "0 0 1 * *" --tz America/Denver  # midnight, 1st of every month, in Denver
explain-cron "@daily" --count 3

Programmatic API

import { explain, formatResult } from 'explain-cron';

const result = explain('*/5 * * * *', { count: 10, tz: 'UTC' });
console.log(result.description);  // "Every 5 minutes"
console.log(result.nextRuns);     // Date[]
console.log(formatResult(result, { tz: 'UTC' }));

Free vs Pro

Free (this package): standard 5-field cron syntax — minute hour day-of-month month day-of-week — plus common @aliases (@daily, @hourly, etc.).

Pro ($9, one-time): the cron dialects that trip people up.

• AWS EventBridge — 6-field syntax, ? placeholders, year field, and the day-of-week-vs-day-of-month exclusivity rule
• GitHub Actions — UTC-only, 5-minute minimum interval, quirks with workflow_dispatch
• Kubernetes CronJob — spec.timeZone field, concurrencyPolicy gotchas, startingDeadlineSeconds

Pro lands soon. Get early access at builtbyzero.com.

explain-cron --pro

Why this exists

Every dev has copy-pasted a cron expression they only half-understand. explain-cron is the 5-second sanity check before you ship the job that wakes you up at 3am.

License

MIT © builtbyzero