What crontab syntax is supported?

Standard 5-field cron (minute hour day-of-month month day-of-week), 6-field cron (with a seconds field prefix), and the @-shortcuts: @reboot, @yearly, @annually, @monthly, @weekly, @daily, @midnight, and @hourly.

How are comments and blank lines handled?

Lines starting with # are treated as comments and displayed as-is. Blank lines are skipped. Inline comments (text after the command following a #) are preserved in the command column.

What does "day-of-month AND day-of-week" mean?

When both fields are non-wildcard, standard cron uses OR logic — the job fires if either condition matches. The parser notes this behavior in the explanation.

Are the next run times in UTC?

No. All timestamps are calculated and displayed in your browser's local timezone. No data is sent to any server.

Does this support vixie-cron environment variables?

Lines like MAILTO=admin@example.com or PATH=/usr/bin are recognized as environment variable assignments and displayed, but they do not affect schedule calculation.

What is the maximum crontab size?

There is no hard limit. The parser processes every non-blank line. For very large files with hundreds of jobs, rendering may take a moment.

Crontab Parser

Name: Crontab Parser
Availability: InStock
Author: Nham Vu

Paste a full crontab (or one expression) and instantly see what each line does, when it next runs, and any errors.

Crontab Input

Paste crontab or expression

5-field, 6-field, @shortcuts, env vars, and comments all accepted.

Examples

Paste a crontab on the left and click Parse.

Supports full crontab files, single expressions, @shortcuts, and env var lines.

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Summary

Paste a full crontab (or one expression) and instantly see what each line does, when it next runs, and any errors.

How it works

Paste your full crontab file or a single cron expression into the input box.
Click Parse to analyze every line.
Read the plain-English schedule description for each job.
Check the next 5 run times (in your browser timezone) for each expression.
Use the Examples dropdown to explore common crontab patterns.

Use cases

Understand a crontab left by a previous developer or sysadmin.
Verify a new cron job fires at exactly the intended times.
Spot impossible or conflicting expressions before they cause issues.
Audit all scheduled jobs on a server at a glance.
Learn cron syntax by seeing plain-English explanations side by side.
Share a readable version of a crontab with non-technical colleagues.

Frequently Asked Questions

Last updated: 2026-06-09 · Reviewed by Nham Vu