Cron Parser

A Cron Parser reads a cron expression such as 0 9 * * 1-5 and explains it in plain words, then lists the next 5 times the job will run. ToolPeko handles lists, ranges, steps and weekday names, runs in your browser, and asks for no upload and no sign-up.

How the Cron Parser works

Type an expression and the reading appears at once. The whole schedule is summed up in one plain line, each of the five fields gets its own explanation, and the next 5 run times are listed under the reading.

1. Type or paste a five field expression, for example */15 * * * *.
2. Or use a ready alias: @hourly, @daily, @weekly, @monthly or @yearly.
3. Read the plain words summary for the whole schedule in one line.
4. Check the five field lines to see what each part means.
5. Read the next 5 run times and confirm the job fires when you expect.

The fields accept more than single numbers. A list such as 1,15 in the day of month field means the 1st and the 15th. A range such as 1-5 means Monday to Friday in the day of week field. A step such as */10 in the minute field means every 10 minutes, and steps pair with ranges. Month and weekday names work too, so JAN and MON are welcome.

Where a Cron Parser prevents a 3 a.m. surprise

Most people meet cron by inheriting it. A server set up by someone else carries a crontab full of lines nobody wants to touch. Paste each line here and the guesswork goes away. You find out which job fills the disk with backups, and which one meant to run monthly actually runs daily.

The second case is writing a new schedule. Backups, reports, cleanup scripts and reminder emails all begin as a row of stars and numbers. Reading the expression back in plain words, and seeing the next 5 run times in a list, is the cheapest review a schedule will ever get. One swapped field turns a weekly report into a job that fires every minute, and the run list shows that in seconds.

The third case is the argument. A job ran on an unexpected day, or skipped an expected one, and two people read the same expression two different ways. The parser settles it, especially the day rule, which catches out careful administrators.

Cron Parser rules and honest limits

The rule most explainers leave out is the one that bites hardest. When both day fields are restricted, standard cron does not wait for a day that matches both. It runs when either one matches. So 0 9 1 * 1 runs at 09:00 on the 1st of every month and on every Monday, which is far more often than most people meant. This page spells out both fields so the wider reading is visible before you save the line.

Standard cron has five fields and stops there. There is no seconds field and no year field. Six and seven field expressions belong to other schedulers, such as Quartz, and they follow different rules. Paste one here and it will not read as standard cron, because it is not. The aliases cover the common cases, @hourly through @yearly, and each expands to a five field form.

Some expressions name a date that never comes. The 31st of February does not exist, and a job set for it will never fire. When that happens, this parser searches the next 2 years and reports no run found, instead of hanging or inventing a date. One more boundary: this page explains expressions and lists run times. It does not run, watch or monitor your jobs. That still belongs to your server.

Your expressions stay on your device

The parsing runs in your browser. Expressions are not sent to a server, not stored by ToolPeko and not tied to any account. Paste a line from a live server and it stays as private as the machine it came from. There is no daily cap and no run limit.