Developer & Data

Cron Expression Builder

Build, explain and preview cron schedules in plain English.

Cron expression

Five fields, or six with a leading seconds field.

Field builder

Each control rewrites its own field in the expression above.

Field breakdown

FieldValueAllowed rangeMatches

Next run times

Calculated in your local time zone ().

Ready-to-paste snippets

Preset library

Click any preset to load it.

Tools that work together with Cron Expression Builder.

All Developer & Data tools
Works withDate & Duration CalculatorDate difference, add/subtract, working days, age and deadlines.Works withWorld Clock & Meeting PlannerCompare time zones and find a working-hours overlap.Works withCodeStudio PlaygroundRun Python, JavaScript, SQL and HTML live; study reference programs in 8 more languages.Works withUUID & ID GeneratorBulk UUID v4/v7, ULID, NanoID, slugs and secure tokens.Developer & DataData Architect StudioConvert JSON, CSV, YAML, XML and SQL; generate mock data; decode JWT and epoch.Developer & DataCode Beautifier & FormatterFormat and minify HTML, CSS, JS, JSON, SQL, YAML and Markdown.Developer & DataSQL & Database StudioDesign schemas and run real SQL on an in-browser SQLite engine.Developer & DataJSON StudioValidate, explore, query, diff and transform JSON with a tree view.

About Cron Expression Builder

Build and decode cron expressions without guesswork. Compose a schedule field by field, read a plain-English explanation, preview the next run times and pick from a library of common presets for Linux, Jenkins, Kubernetes and Spring.

What it does

How to use it

  1. Type a cron expression, or build one field by field with the pickers below.
  2. Read the plain-English explanation to confirm the schedule means what you intended.
  3. Check the list of upcoming run times, which is calculated from your own clock.
  4. Copy the expression, or copy a ready-made crontab, Kubernetes CronJob or Spring annotation line.

Cron Expression Builder is one of 50 free tools from CRMTECH Solutions. See all Developer & Data tools or browse every tool.

Frequently asked questions

Which cron dialects are supported?

Standard 5-field Unix crontab (minute, hour, day-of-month, month, day-of-week) and 6-field Quartz style with a leading seconds field. Step values (*/5), ranges (1-5), lists (1,3,5), names (MON, JAN) and the @hourly style macros are all understood.

How are the next run times calculated?

By stepping forward minute by minute from the current time in your browser's own time zone and testing each candidate against the expression. No server clock is involved, so the times shown are local to this machine.

What happens when both day-of-month and day-of-week are set?

In standard cron the two are ORed, not ANDed: the job runs if either field matches. The explanation states this explicitly when it applies, because it is the single most common cron mistake.

Is the output safe to paste into a real crontab?

Yes. The tool only formats text; it never executes anything. Always review the generated line and test with a harmless command first.

Why does my expression show no upcoming runs?

Usually because it is impossible, such as 30 February, or because the search window of one year contains no match. The validator flags impossible day and month combinations.

Is Cron Expression Builder free?

Yes. Cron Expression Builder is free for everyone and needs no sign-up to use. An account is only needed to export, download or print, because every export is recorded.

Are my files uploaded to a server?

No. Cron Expression Builder works inside your web browser, so the files you open are processed on your own device. If you sign in, the work you save (such as drafts and registers) is also kept in your account so it follows you to other devices.

Does it work on a phone?

Yes. It works in current versions of Chrome, Edge, Safari and Firefox on phones, tablets and computers, with nothing to install.