About CronGen
A free developer tool for building cron expressions visually.
What Is CronGen?
CronGen is a free, online cron expression generator designed for developers, system administrators, and DevOps engineers. It provides a visual interface to build, validate, and understand cron job schedules without memorizing the cryptic five-field syntax.
Instead of guessing whether */15 9-17 * * 1-5 does what you think it does, CronGen shows you a human-readable description, highlights each field with color-coded labels, and displays the next five scheduled run times so you can verify the schedule before deploying it.
Why We Built It
Cron syntax is powerful but easy to get wrong. Swapping the hour and minute fields, confusing day-of-month with day-of-week, or forgetting how the step operator works are mistakes that even experienced developers make. A misconfigured cron job can mean missed backups, duplicate emails, or runaway resource consumption.
We built CronGen to eliminate that guesswork. The tool provides instant feedback as you adjust each field, making it easy to experiment with different schedules. Preset templates cover common patterns like "every 5 minutes," "weekdays at 9 AM," and "monthly on the 1st," so you can start from a known-good schedule and customize from there.
CronGen is entirely client-side. Your cron expressions are built in your browser and never sent to any server. There are no accounts, no tracking, and no data collection. The tool is and will remain free to use.
Key Features
Visual Builder
Adjust each cron field with dropdowns and text inputs. See the expression update in real time.
Preset Schedules
16 common cron patterns from every minute to yearly, ready to use with one click.
Human Descriptions
Instant plain-English translation of any cron expression so you know exactly what it does.
Next Run Preview
See the next 5 scheduled execution times to verify the schedule matches your intent.
Syntax Highlighting
Each field is color-coded (minute, hour, day, month, weekday) for easy reading.
One-Click Copy
Copy the generated expression to your clipboard and paste it directly into crontab.
Dark & Light Themes
Switch between themes based on your preference or system settings.
Completely Free
No sign-up, no limits, no premium tier. The full tool is free forever.
Technology
CronGen is built with modern web technologies for fast performance and a great developer experience:
- Next.js — React framework with server-side rendering and static generation for fast page loads and excellent SEO.
- Tailwind CSS — Utility-first CSS framework for a responsive, consistent design across all devices.
- TypeScript — Full type safety across the codebase for reliability and maintainability.
- Vercel — Deployed on Vercel's edge network for low-latency access worldwide.
Who Is It For?
CronGen is designed for anyone who works with cron schedules:
- Backend developers configuring scheduled tasks in their applications.
- DevOps and SRE teams managing crontab entries on servers and Kubernetes clusters.
- System administrators setting up backup, monitoring, and maintenance schedules.
- Students and beginners learning cron syntax for the first time.
- Anyone who needs to quickly generate a cron expression without memorizing the field order.
Open Source
CronGen is open source and available on GitHub. Contributions, bug reports, and feature requests are welcome. If you find the tool useful, consider starring the repository to help others discover it.
Contact
Have feedback, questions, or suggestions? Reach out via GitHub Issues or email contact@crongen.dev.