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Cron Expression Parser & Builder

Development Client-side cron crontab scheduler expression parser builder generator

This tool runs entirely client-side, in your browser: your data is never sent anywhere.

What it does

Two tools in one:

Builder — pick a schedule using simple dropdowns (every minute, hourly, daily, weekly, monthly), or use the custom field builder for anything else — every field is chosen from validated pickers, so it's impossible to generate an invalid cron expression.
Parser — paste any standard 5-field cron expression (minute hour day-of-month month day-of-week) to get a plain-English explanation plus the next several times it would actually run.

Try it

🛠️ Build a cron expression

Schedule type Generated expression

How it works

Builder presets

Every minute → *
Hourly → <minute> , at the chosen minute of every hour.
Daily → <minute> <hour> * at the chosen time every day.
Weekly → <minute> <hour> <day-of-week> at the chosen time, on the chosen weekday only.
Monthly → <minute> <hour> <day-of-month> at the chosen time, on the chosen day of the month.

Custom field builder

Each of the 5 fields (minute, hour, day-of-month, month, day-of-week) has its own match mode, chosen from a dropdown — no free typing of the cron syntax itself is required:

**Every value (*)** — matches all values for that field.
**Every N units (*/n)** — a step picker (e.g. every 15 minutes).
Specific value(s) — a multi-select list of the valid values for that field (e.g. pick Monday + Wednesday + Friday for day-of-week); generates a comma-separated list like 1,3,5.
Range (a-b) — two dropdowns, "from" and "to", both restricted to the field's valid range, generating a-b.

Because every dropdown is pre-populated with only the legal values for that field (0-59 for minutes, 0-23 for hours, 1-31 for day-of-month, 1-12 for months shown by name, 0-6 for day-of-week shown by name), the resulting expression is always syntactically valid.

Parser

Each of the 5 fields is parsed for the standard cron syntax: (every value), /n (every n units), a-b (range), a,b,c (list), and combinations like 1-5,10.
A plain-English description is built from the parsed fields (e.g. "At every 15th minute, past every hour from 9 through 17, on every day-of-week from Monday through Friday").
To find upcoming run times, the tool simulates minute-by-minute starting from now (in your local timezone) and checks each field's match, stopping once 5 matching future times are found (searching up to 2 years ahead as a safety limit).

Everything runs locally in your browser — nothing is uploaded anywhere.