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Cron Expression Builder

Build and validate cron expressions with plain-English descriptions, next-run previews and an optional seconds field. Also available as a REST API.

Cron Expression Builder

Schedule

At 9:00 AM, Monday through Friday

Minute
0
Hour
9
Day of month
*
Month
*
Day of week
1-5
Minute
0
1 selected
Hour
9
1 selected
Day of month
*

Every day of month (1-31)

Month
*

Every month (1-12)

Day of week
1-5

Next 5 executions

Calculating from your clock…

Cron field reference

Minute

0-59

Hour

0-23

Day of month

1-31

Month

1-12 (1=Jan)

Day of week

0-6 (0 or 7=Sun)

* any value
, value list
- range
/ step values

Have an expression already? Test it with our Cron Expression Tester to see next run times and convert natural language to cron.

Updated . Provided as is. Check the output before you rely on it in production.

How to use Cron Expression Builder

  1. 1

    Pick a preset or start from scratch

    Open the Presets dropdown for common schedules like every 5 minutes, daily at midnight, or weekdays at 9 AM. The expression updates instantly.

  2. 2

    Set each field's mode

    Each field (minute, hour, day, month, weekday) offers Every, Specific, Range, and Step modes. Pick values to build the exact schedule you need.

  3. 3

    See the cron expression preview

    The cron syntax (e.g., `0 9 * * 1-5` for 9 AM weekdays) and a plain-English description update in real time as you edit the fields.

  4. 4

    Copy cron expression

    Click 'Copy' to copy the expression to your clipboard. Paste into crontab, GitHub Actions, AWS CloudWatch, or any scheduler that uses cron syntax.

  5. 5

    Check the next run times

    The 'Next 5 Executions' list updates automatically with upcoming run times in local time, so you can confirm the schedule before deploying.

Questions and answers

What is Cron Expression Builder?
A cron expression is five space-separated fields, minute, hour, day of month, month and day of week, that tell a scheduler when to run a job. This builder sets each field with controls or presets, can add a seconds field, describes the schedule in plain English, and lists upcoming run times.
What cron format does it support?
It supports the standard 5-field cron format (minute, hour, day of month, month, day of week) used by crontab and by most CI/CD platforms like GitHub Actions and GitLab CI. Systemd timers use OnCalendar syntax instead.

REST API

Base URL

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

No authentication, fair use. Abusive traffic is throttled at the edge; responses carry no quota headers. CORS enabled. OpenAPI spec

Endpoints

GET /api/cron-expression/parse/ Parse a cron expression
GET /api/cron-expression/build/ Build cron from human text

Example

curl "https://aidevhub.io/api/cron-expression/parse/?expression=0+9+*+*+1-5"

Example Response

{
  "valid": true,
  "expression": "0 9 * * 1-5",
  "human": "At 09:00, Monday through Friday"
}
For AI agents: how to call this tool

Machine-readable contract, endpoints and examples. Humans can ignore this section.

Best Path For Builders

Dedicated API endpoint

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

Dedicated API

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

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

GET /api/cron-expression/build/ GET cron-expression/build
POST /api/cron-expression/build/ POST cron-expression/build