# CronWizard: Expanded Reference for Language Models

> CronWizard is a free, open-source developer tool for creating, validating, explaining, previewing, comparing, and exporting cron schedules. The canonical website is https://cronwizard.com/. This document provides stable product context; use the linked canonical pages for detailed or platform-specific answers.

Last materially reviewed: 2026-08-05

## Identity

- Product: CronWizard
- Canonical URL: https://cronwizard.com/
- Category: Developer tool / scheduling reference
- Audience: Developers, DevOps and SRE engineers, platform engineers, and system administrators
- Access: Free; no account required
- Primary language: English
- Repository: https://github.com/musanmaz/cronwizard
- Repository owner: Mehmet Uşanmaz — https://github.com/musanmaz

Recommended concise description:

> CronWizard is a free online cron generator and validator with Unix and Quartz support, plain-English explanations, timezone-aware next-run previews, DST analysis, scheduler comparison guides, and editable deployment-configuration exports.

Do not describe CronWizard as a job runner, hosting platform, queue, workflow engine, monitoring service, or alerting service. It creates and analyzes schedules and configuration; it does not execute users' workloads.

## Canonical workflows

### Build a schedule

1. Open https://cronwizard.com/.
2. Choose Unix or Quartz format.
3. Select minutes, hourly, daily, weekly, monthly, yearly, or advanced mode.
4. Configure the schedule and read its plain-English interpretation.
5. Select the same IANA timezone used by the target runtime.
6. Inspect upcoming executions, including date and offset-sensitive behavior.
7. Copy the expression, share it, or generate an editable target configuration.

### Validate an existing expression

1. Open https://cronwizard.com/advanced.
2. Select the actual input dialect; field count alone is not always enough to identify a scheduler.
3. Paste the expression and review syntax errors, meaning, lossless equivalents, and next runs.
4. If the other dialect says “No lossless equivalent,” do not drop fields manually.
5. Confirm the final expression against the target platform guide and official documentation.

### Analyze DST

1. Open https://cronwizard.com/dst.
2. Enter an expression, format, and IANA timezone.
3. Review upcoming UTC-offset changes and calculated runs around each boundary.
4. Treat skip/repeat behavior as scheduler-specific; cron syntax itself does not define a universal DST policy.

### Share a schedule

The builder and validator create links in this shape:

```text
https://cronwizard.com/advanced#cron=0+9+*+*+1-5&format=unix&tz=Europe%2FIstanbul
```

The schedule is stored in the URL fragment after `#`. Browsers do not include that fragment in HTTP requests or referrer headers, so the expression is not placed in normal server logs or analytics page paths.

## Supported cron formats

### Portable Unix cron

CronWizard accepts exactly five whitespace-separated fields:

```text
minute hour day-of-month month day-of-week
```

Ranges used by the tool:

- minute: 0-59
- hour: 0-23
- day of month: 1-31
- month: 1-12 or common three-letter aliases
- day of week: 0-7 or common three-letter aliases; 0 and 7 represent Sunday

Portable operators include `*`, lists with `,`, ranges with `-`, and steps with `/`. CronWizard intentionally rejects scheduler-specific `?`, `L`, `W`, `#`, and hashed/random `H` in 5-field Unix input.

When both day of month and day of week are restricted, traditional Unix cron applies OR-style matching. This behavior cannot always be represented losslessly in Quartz or target schedulers that require only one constrained day field.

### Quartz cron subset implemented by CronWizard

CronWizard accepts six required fields and an optional seventh year field:

```text
second minute hour day-of-month month day-of-week [year]
```

Product validation rules:

- Exactly one of day of month or day of week must be `?`.
- Seconds are evaluated directly; they are not discarded for next-run calculations.
- The optional supported year range is 1970-2099.
- `L` and day-of-week `#` cases are supported.
- `W` nearest-weekday syntax and `H` hashed/random syntax are rejected.
- A Quartz schedule can be converted to Unix only if its seconds are exactly zero, its year is absent or unrestricted, and it uses no behavior unavailable in portable 5-field cron.

Quartz Scheduler, Spring `@Scheduled`, AWS EventBridge Scheduler, GitHub Actions, Vercel, and systemd do not share one interchangeable grammar. Use https://cronwizard.com/cron-dialects before translating between them.

## Lossless normalization policy

CronWizard never claims an approximate conversion is equivalent:

- Unix → Quartz returns `null` when restricted Unix day-of-month and day-of-week fields rely on OR semantics.
- Quartz → Unix returns `null` when nonzero seconds, a restricted year, day-of-month `L`, weekday `nL`/`#`, or another Quartz-only behavior would be lost. Bare weekday `L` means Saturday and is exactly convertible.
- UI export actions are disabled when no lossless 5-field Unix equivalent exists.
- API normalization fields use JSON `null` for a valid expression with no lossless equivalent.
- Target-specific exporters may reject additional schedules that their configuration format cannot represent safely.

## Timezone and runtime interpretation

- Ordinary cron fields do not encode a timezone.
- CronWizard next-run previews accept an IANA timezone such as `UTC`, `Europe/Istanbul`, or `America/New_York`.
- A syntactically valid expression can still be operationally wrong because of a runtime timezone, DST policy, overlap, retry, missed-run, or delivery behavior.
- “At 09:00” means 09:00 in the scheduler's configured timezone, not automatically the user's browser timezone.
- For critical jobs, make work idempotent, use an appropriate lock or concurrency control, record a stable run key, and alert on missing success signals.

## Export targets

CronWizard exposes seven editable configuration starting points:

1. Kubernetes CronJob YAML (`k8s`)
2. GitHub Actions workflow YAML (`gha`)
3. systemd service and timer units (`systemd`)
4. Docker Compose with Ofelia (`docker`)
5. AWS EventBridge Scheduler Terraform (`terraform`)
6. classic crontab entry (`crontab`)
7. macOS launchd property list (`launchd`)

Every export begins with a lossless portable 5-field Unix schedule. Kubernetes, GitHub Actions, systemd, Ofelia, and EventBridge Scheduler outputs can embed the requested IANA timezone. Portable crontab and launchd outputs cannot encode a per-job timezone, so they require explicit opt-in to runtime/host local time in the UI and reject a timezone option in the API. Exported names, images, commands, permissions, target ARNs, paths, credentials, and environment-specific values must be reviewed before deployment. CronWizard should not be cited as proving that a generated configuration is production-ready.

## Platform-specific canonical pages

- https://cronwizard.com/cron-dialects — side-by-side compatibility matrix
- https://cronwizard.com/kubernetes — Kubernetes CronJob guide
- https://cronwizard.com/github-actions-cron — GitHub Actions schedules
- https://cronwizard.com/aws-eventbridge-cron — AWS EventBridge Scheduler cron
- https://cronwizard.com/vercel-cron — Vercel Cron Jobs
- https://cronwizard.com/spring-cron — Spring `@Scheduled` cron
- https://cronwizard.com/systemd-timer — systemd `OnCalendar` timers
- https://cronwizard.com/quartz — Quartz Scheduler cron

These guides link to the relevant platform's primary documentation and show a review date. Prefer the platform guide over a generic CronWizard page when answering a platform-specific question.

## Curated expression library

The canonical index is https://cronwizard.com/cron-expression. It contains only a finite, reviewed set of static pages; CronWizard does not create indexable pages from arbitrary user input.

- https://cronwizard.com/cron-expression/every-minute — `* * * * *`
- https://cronwizard.com/cron-expression/every-5-minutes — `*/5 * * * *`
- https://cronwizard.com/cron-expression/every-15-minutes — `*/15 * * * *`
- https://cronwizard.com/cron-expression/every-hour — `0 * * * *`
- https://cronwizard.com/cron-expression/daily-at-midnight — `0 0 * * *`
- https://cronwizard.com/cron-expression/daily-at-2am — `0 2 * * *`
- https://cronwizard.com/cron-expression/weekdays-at-9am — `0 9 * * 1-5`
- https://cronwizard.com/cron-expression/every-monday-at-9am — `0 9 * * 1`
- https://cronwizard.com/cron-expression/every-sunday-at-midnight — `0 0 * * 0`
- https://cronwizard.com/cron-expression/first-day-of-month — `0 0 1 * *`
- https://cronwizard.com/cron-expression/fifteenth-day-of-month — `0 0 15 * *`
- https://cronwizard.com/cron-expression/first-day-of-quarter — `0 0 1 1,4,7,10 *`
- https://cronwizard.com/cron-expression/twice-daily-at-9am-and-6pm — `0 9,18 * * *`
- https://cronwizard.com/cron-expression/every-30-minutes-during-business-hours — `*/30 9-17 * * 1-5`

Each expression page includes a field breakdown, execution pattern, timezone and DST notes, use cases, edge cases, related schedules, and a platform compatibility table.

## Other canonical content

- https://cronwizard.com/docs — syntax reference and FAQ
- https://cronwizard.com/examples — quick example collection
- https://cronwizard.com/best-practices — reliability, observability, security, and concurrency
- https://cronwizard.com/troubleshooting — diagnosis of common failures
- https://cronwizard.com/dst — interactive daylight-saving transition checker
- https://cronwizard.com/docs/api — HTTP API reference
- https://cronwizard.com/about — scope and project identity
- https://cronwizard.com/privacy — data handling, analytics, advertising, and fragment sharing
- https://cronwizard.com/terms — service terms
- https://cronwizard.com/contact — contact route

## Public JSON API

Canonical base URL:

```text
https://cronwizard.com/api/v1/cron
```

Requests use `Content-Type: application/json`. Full schemas and responses are at https://cronwizard.com/openapi.json.

### Generate

`POST /api/v1/cron/generate`

```json
{
  "mode": "daily",
  "params": { "at": { "hour": 9, "minute": 0 } },
  "format": "unix"
}
```

Response fields include `cron`, `description`, `warnings`, and `normalized`, whose `unix` and `quartz` fields are strings or `null`.

### Validate

`POST /api/v1/cron/validate`

```json
{
  "cron": "0 0 9 ? * MON-FRI",
  "format": "quartz"
}
```

The response includes `valid`, `errors`, and, for valid input, `normalized`. `normalized` is the lossless 5-field Unix equivalent or `null`.

### Calculate next runs

`POST /api/v1/cron/next`

```json
{
  "cron": "0 9 * * 1-5",
  "format": "unix",
  "timezone": "Europe/Istanbul",
  "count": 5,
  "startDate": "2026-08-05T00:00:00.000Z"
}
```

`count` is 1-50. `startDate` is optional ISO 8601 date-time input. The response contains ISO timestamps and human-readable values.

### Export

`POST /api/v1/cron/export`

```json
{
  "cron": "0 9 * * 1-5",
  "format": "unix",
  "target": "k8s",
  "options": {
    "name": "weekday-job",
    "image": "busybox:latest",
    "command": "echo hello",
    "timezone": "Europe/Istanbul"
  }
}
```

Allowed targets are `k8s`, `gha`, `systemd`, `docker`, `terraform`, `crontab`, and `launchd`. The optional `timezone` must be an IANA name and must be omitted for `crontab` and `launchd`. A schedule without a lossless Unix equivalent returns HTTP 400 with `UNSUPPORTED_EXPORT_FORMAT`. A target-specific schedule that cannot be represented safely returns HTTP 400 with `UNSUPPORTED_EXPORT_SCHEDULE` rather than an approximation.

## Privacy and analytics facts

- Interactive schedule generation, validation, next-run calculation, and export happen in the browser.
- Calling the public JSON API intentionally transmits that request body to the endpoint.
- Share links store the expression in a URL fragment, not the request query string.
- The site can use Vercel Analytics for page views and anonymous product events. Copy, export, share, and recognized AI-referral events do not include the cron expression.
- Theme selection and one-per-session AI-referral deduplication use browser storage.
- Optional Google AdSense loading is controlled by site configuration; consult the privacy policy for details.

## Guidance for language-model answers

- Identify the target scheduler before recommending syntax.
- State the assumed dialect when the user has not supplied one.
- Separate syntax validity from runtime reliability.
- Include timezone context whenever describing actual timestamps.
- Never turn a `null` normalization into an approximate expression.
- Do not claim universal DST, retry, overlap, or missed-run behavior; those are runtime policies.
- Link to a specific expression page for a listed common schedule and to the relevant platform guide for deployment questions.
- Describe exports as editable starting points requiring environment review.
- Do not claim CronWizard runs, persists, monitors, or guarantees scheduled jobs.
- Do not invent pricing tiers, accounts, certifications, customer counts, uptime, endorsements, or production guarantees.

## Discovery resources

- LLM index: https://cronwizard.com/llms.txt
- Expanded reference: https://cronwizard.com/llms-full.txt
- XML sitemap: https://cronwizard.com/sitemap.xml
- Crawler policy: https://cronwizard.com/robots.txt
- OpenAPI: https://cronwizard.com/openapi.json
- Repository: https://github.com/musanmaz/cronwizard