Cron is one of the most widely used job schedulers in the world and remains one of the simplest ways to automate recurring backend work.
Whether you’re sending emails, syncing data, cleaning up records, or triggering background jobs, cron-style scheduling still quietly runs a massive portion of the internet: from Linux servers to cloud platforms to no-code tools like Xano.
This guide explains what cron jobs are, how they work, and how the same concepts show up in modern platforms today.
What is a cron job?
A cron job is a scheduled task that runs automatically at a specific time or interval. A newsletter is emailed out every Saturday at 4:00 PM. Data is deduplicated in the production database every day at 3:00 AM. Every 30 seconds, the system checks how much disk space is left.
Cron is a time-based job scheduler originally built for Unix-like operating systems. A cron job is any task that runs automatically at a scheduled time or interval using cron syntax.
You’ll also hear cron jobs called automations: it’s just a more friendly way of saying time-based, recurring execution.
Common use cases include:
- Running backups
- Syncing data between systems
- Cleaning up old files or logs
- Triggering background workflows
- Monitoring system health
- Sending scheduled notifications
Even if you never touch a Linux terminal, you will encounter cron concepts inside tools like GitHub Actions, Kubernetes CronJobs, cloud schedulers, and backend platforms like Xano.
How do cron jobs work?
At their core, cron jobs sync to a server’s clock and execute a piece of code at specific times.
That might be:
- Every minute
- Every hour
- Every day
- Or once a month
Cron itself does not contain any business logic.It’s just the scheduling layer: the thing that decides when your code runs.
The actual work, (such as sending emails, processing data, generating reports, triggering workflows) is handled by your application.
Cron job syntax: The basics
A basic cron expression looks like this:
* * * * *
Each position represents a unit of time:
Minute (0–59)
Hour (0–23)
Day of month (1–31)
Month (1–12)
Day of week (0–6, where 0 is Sunday)
When all five fields are asterisks, the job runs every minute.
For example:
0 3 * * *
Runs every day at 3 AM.
*/5 * * * *
Runs every 5 minutes.
0 9-17 * * 1-5
Runs every hour from 9 AM to 5 PM, Monday through Friday.
Special characters you should know
Cron becomes more powerful when you use special characters:
- * — every value
- - — a range
- , — a list
- / — step values
Examples:
*/5 * * * * → every 5 minutes
0 0 1,15 * * → on the 1st and 15th of each month
0 9-17 * * 1-5 → business hours on weekdays
Special time strings
Many cron implementations support shortcuts:
- @hourly
- @daily or @midnight
- @weekly
- @monthly
- @yearly
These make common schedules easier to read and less error-prone.
Modern cron gotchas and best practices
Cron looks simple, but real-world usage introduces complexity:
- Time zones and daylight saving: Jobs may run twice or not at all if the server time shifts. Many teams standardize on UTC.
- Environment variables: Cron runs in a minimal environment. Paths and credentials must be defined explicitly.
- Logging: Cron is silent by default—always log output.
- Idempotency: Jobs should be safe to run more than once without creating duplicates.
- Overlapping runs: If a job runs longer than its interval, executions can overlap unless protected.
Cron in cloud and no-code platforms
Cron scheduling now exists everywhere:
- Kubernetes CronJobs
- GitHub Actions schedules
- Cloud function schedulers
- No-code backends like Xano
These platforms add retries, logging, and monitoring on top of traditional cron concepts. You still get the same scheduling power—you just don’t have to manage servers anymore.
How Xano uses cron concepts
Xano abstracts cron into scheduled background tasks.
You can:
- Run workflows on a schedule
- Sync APIs
- Clean data
- Generate reports
- Trigger backend logic
All without managing Linux servers or writing crontab files.
When should I NOT use a cron?
Cron is best for predictable, time-based work. It is not ideal for:
- Event-driven actions
- Real-time systems
- Complex conditional logic
- User-triggered flows
For those, queues, webhooks, or event systems are better fits.
The bottom line
Cron remains one of the most important automation concepts in software. The syntax may look strange at first, but the idea is simple: Run code on a schedule. Whether you’re working in Linux, the cloud, or a no-code backend, cron concepts are everywhere, and understanding them lets you automate almost anything.
Xano gives you the power of cron scheduling with a modern, scalable backend—no servers required. See for yourself by trying it out for free!
