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Cron Expression Tester

minhourdaymondow

Quick Presets

✓ Valid Expression

At 09:00, on weekdays

Field Breakdown

Minute

0

0-59

Hour

9

0-23

Day of Month

*

1-31

Month

*

1-12

Day of Week

1-5

0-7 (Sun-Sat, 7=Sun)

Next 10 Runs(UTC)

#Date & TimeDayRelative
1Jul 20, 2026, 09:00Mondaytomorrow
2Jul 21, 2026, 09:00Tuesdayin 2 days
3Jul 22, 2026, 09:00Wednesdayin 3 days
4Jul 23, 2026, 09:00Thursdayin 4 days
5Jul 24, 2026, 09:00Fridayin 5 days
6Jul 27, 2026, 09:00Mondayin 1 weeks
7Jul 28, 2026, 09:00Tuesdayin 1 weeks
8Jul 29, 2026, 09:00Wednesdayin 1 weeks
9Jul 30, 2026, 09:00Thursdayin 1 weeks
10Jul 31, 2026, 09:00Fridayin 1 weeks
🔗

Want to build visually? Use the Cron Expression Builder to create cron expressions with dropdowns and toggles.

What This Tool Does

Cron Expression Tester is built for deterministic developer and agent workflows.

Test cron expressions and see next run times in your timezone. Generate cron from natural language like 'every Monday at 9am'. Free, private,.

Use How to Use for execution steps and FAQ for constraints, policies, and edge cases.

Last updated:

This tool is provided as-is for convenience. Output should be verified before use in any production or critical context.

Programmatic Access

Cron Expression Tester is also callable as a free HTTP JSON API at https://aidevhub.io/api/cron-expression/parse/ — GET with query parameters or POST with a JSON body, no authentication, CORS enabled, 50 requests/day per IP. Responses return { ok, tool, result, meta }. 

curl -s "https://aidevhub.io/api/cron-expression/parse/?expression=0%209%20*%20*%201-5"

Machine-readable contract: /api/tool/cron-tester.json All API endpoints: /agents/ LLM site index: /llms.txt

Agent Invocation

Best Path For Builders

Dedicated API endpoint

Deterministic outputs, machine-safe contracts, and production-ready examples.

Dedicated API

https://aidevhub.io/api/cron-expression/parse/

OpenAPI: https://aidevhub.io/api/openapi.yaml

GET /api/cron-expression/parse/ GET cron-expression/parse
POST /api/cron-expression/parse/ POST cron-expression/parse

Unified Runtime API

https://aidevhub.io/api/tools/run/?toolId=cron-tester&a=...

GET and POST are supported at /api/tools/run/ with identical validation and limits.

Limit: 60 req / 60s, input max 128 KB.

How to Use Cron Expression Tester

  1. 1

    Validate cron expression syntax

    Paste cron expression: '0 8 * * MON' (every Monday 8am). Tester checks syntax, converts to English ('At 08:00 on Monday'), and shows next 5 run times. Catch typos before deployment.

  2. 2

    Calculate next run time for scheduled jobs

    Need to know when your backup cron runs next? Paste expression and current date. Tester shows exact next run datetime. Useful to verify job schedules before SLA commitments.

  3. 3

    Convert natural language to cron expression

    Want 'every 15 minutes' or 'daily at 3pm on weekdays'? Describe it, tester suggests cron. Verify suggested cron is correct by checking next 10 run times.

  4. 4

    Debug cron jobs that don't run

    If a job never ran, check if cron expression is valid. Paste into tester. If it says 'invalid', that's why job never ran. Fix syntax and redeploy.

  5. 5

    Plan maintenance windows with cron insights

    Paste all job crons (hourly backup, nightly cleanup, weekly reports). Tester shows overlap. If too many jobs run at same time, reschedule one to reduce load. Stagger crons efficiently.

Frequently Asked Questions

What is a cron expression?
A cron expression is a string of 5 fields (minute, hour, day of month, month, day of week) that defines a recurring schedule. It's used by crontab, systemd timers, CI/CD platforms, and task schedulers to run jobs automatically.
How do I test a cron expression?
Paste your cron expression into the input field, select your timezone, and instantly see the next scheduled run times with human-readable descriptions. The tool supports both 5-field (standard) and 6-field (with seconds) cron formats.
Can I generate cron from natural language?
Yes! Type phrases like 'every Monday at 9am', 'every 5 minutes', 'weekdays at 8:30am', or 'monthly on the 1st at noon' and the tool automatically generates the corresponding cron expression. No API calls — parsing runs entirely in your browser.
Is this cron tester free and private?
Free to use and runs entirely in your browser, your data is not sent to external servers. No account required. Your expressions and schedules stay completely private.
What's the difference between Cron Builder and Cron Tester?
Cron Builder lets you construct cron expressions visually using dropdowns and toggles — ideal when starting from scratch. Cron Tester validates existing expressions, shows when they'll fire, and can generate cron from natural language descriptions.