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Hazuu Tools

Cron Expression Parser

Parse cron expressions into human-readable schedules with field breakdowns and next run times.

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Enter a cron expression and click Parse to see the schedule.
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About Cron Parser

Cron is a time-based job scheduler built into virtually every Unix-like system, cloud platform, and CI/CD pipeline. A cron expression encodes a recurring schedule in five whitespace-separated fields — minute, hour, day of month, month, and day of week — each supporting wildcards, ranges, step values, and comma-separated lists. Reading these compact strings correctly is harder than it looks: a single misplaced asterisk can cause a job to fire every minute instead of once a day, and ranges with steps such as 1-5/2 require careful mental arithmetic to verify.

Cron Parser decodes any standard five-field expression in your browser the moment you click Parse. It produces three outputs in parallel: a plain-English sentence describing the full schedule, a field-by-field breakdown table showing what each token means, and a numbered list of the next ten upcoming run times calculated from your local clock. Together these outputs let you confirm whether an expression does exactly what you intended before it goes anywhere near a production environment.

All parsing and date calculations run entirely in your browser using JavaScript. Your cron expressions are never sent to a server, stored, or logged, so you can safely inspect the schedules of internal automation and proprietary pipelines. There is no account required and no usage limit — paste as many expressions as you need.

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Key Features

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Plain-English schedule summary

Each expression is translated into a readable sentence such as "At 9:00 AM on Monday through Friday" so you can confirm the intent at a glance without memorizing syntax rules.

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Per-field breakdown table

A five-row table shows the raw token for every field alongside its meaning, making it easy to spot which field contains a mistake when a schedule looks wrong.

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Next 10 run times

The tool computes the next ten timestamps the job will fire, displayed in your local timezone, so you can verify the cadence against real calendar dates rather than abstract rules.

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Full syntax support

Handles wildcards (*), step values (*/n), numeric ranges (n-m), range-with-step (n-m/s), comma-separated lists, and named day and month abbreviations such as MON and JAN.

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One-click presets

A presets menu covers ten of the most common schedules — from every minute to the first of every month — so you can load a known-good baseline and edit from there.

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Private and client-side

Parsing happens entirely in the browser. Nothing is uploaded, making it safe to inspect cron expressions from internal systems, private servers, or proprietary pipelines.

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How to Use

01

Enter Expression

Type or paste a five-field cron expression into the input field, or choose one from the Presets menu.

02

Parse

Click the "Parse" button (or press Enter) to analyze the expression and generate the schedule.

03

Review Results

Read the human-readable description, inspect the field breakdown table, and check the next 10 scheduled run times.

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Example

Parsing "0 9 * * 1-5" produces a plain-English description, a per-field table, and the next scheduled run times based on your local clock.

Cron expression
0 9 * * 1-5
Parsed result
Schedule description
At 9:00 AM on Monday through Friday

Field breakdown
Minute      │ 0      │ 00
Hour        │ 9      │ 09
Day-of-month│ *      │ every day-of-month
Month       │ *      │ every month
Day-of-week │ 1-5    │ Monday through Friday

Next runs (your local timezone)
1. Mon, Jun 09, 2025 at 9:00 AM
2. Tue, Jun 10, 2025 at 9:00 AM
3. Wed, Jun 11, 2025 at 9:00 AM
   ... (10 run times total)
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Common Use Cases

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    Auditing an unfamiliar cron schedule

    When you inherit a server or pipeline you did not set up, paste the crontab entries one by one to confirm what each job does and when it runs — without having to decode each field manually.

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    Verifying a schedule before deploying

    Paste the expression you plan to use in production and check the next ten run times against your requirements. Catching an off-by-one in the hour field in the browser is far cheaper than waking up to a midnight job that fires at noon.

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    Debugging unexpected job behavior

    When a scheduled task fires at the wrong time or not at all, paste the cron expression here to see the exact computed schedule. This often reveals range-with-step combinations or timezone mismatches that look correct but evaluate differently.

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    Learning cron syntax interactively

    Try variations of an expression — changing a wildcard to a list, adding a step value, or mixing day-of-month and day-of-week constraints — and read the plain-English description to build an intuition for how the syntax works.

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    Cross-checking a generated schedule

    After writing a cron expression with a crontab generator, paste it into the parser to independently confirm the output matches your intended schedule. The field breakdown makes discrepancies immediately visible.

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Frequently Asked Questions

What is a Cron Parser? expand_more
A cron parser is a tool that takes a cron expression — a five-field string used to define recurring schedules — and translates it into a human-readable description. It helps developers, system administrators, and DevOps engineers understand exactly when their scheduled tasks will run without having to mentally decode the syntax.
What cron syntax is supported? expand_more
This tool supports the standard five-field cron format: minute (0-59), hour (0-23), day of month (1-31), month (1-12 or JAN-DEC), and day of week (0-6 or SUN-SAT). It handles wildcards (*), step values (*/n), ranges (n-m), comma-separated lists (n,m,o), and range-with-step (n-m/s).
Is my data processed securely? expand_more
Yes. All parsing and schedule calculations happen entirely in your browser using JavaScript. No data is ever sent to a server, ensuring your cron expressions and schedule details remain completely private.
Why are the next run times different from what I expect? expand_more
The next run times are calculated based on your local system clock and timezone. If you are comparing against a server in a different timezone (e.g., UTC), the times may differ. Make sure to account for timezone differences when verifying schedules.
How is the Cron Parser different from the Crontab Generator? expand_more
The Cron Parser is a reading tool: you give it an existing expression and it tells you what that expression means and when it will fire. The Crontab Generator is a writing tool: you pick a schedule from a visual form and it produces the cron expression for you. Use the parser to verify or understand expressions, and the generator to create new ones from scratch.
What does the day-of-week and day-of-month interaction mean? expand_more
When both the day-of-month and day-of-week fields are non-wildcards, the standard cron behavior is to match either condition — not both. For example, "0 0 15 * 5" fires at midnight on the 15th of every month AND every Friday, not only on Fridays that fall on the 15th.
Can I use named values like MON or JAN? expand_more
Yes. The tool accepts three-letter abbreviations for days of the week (SUN through SAT) and months (JAN through DEC) in the appropriate fields. For example, "0 8 * * MON-FRI" is equivalent to "0 8 * * 1-5".
Is there a limit on how many expressions I can parse? expand_more
No. Because everything runs locally in your browser, you can parse as many expressions as you need without hitting any rate limits or creating an account.