Cron Schedule for Serverless: GitHub Actions, Vercel Cron, and Cloudflare Workers

Cron expressions are the universal language for scheduling recurring tasks. But when you move from traditional crontab to serverless platforms, each platform has its own quirks, limitations, and syntax differences. This guide covers everything you need to schedule jobs on the three most popular serverless platforms.

Cron Expression Basics (60-Second Refresher)

A standard cron expression has 5 fields:

┌───────────── minute (0-59)
│ ┌───────────── hour (0-23)
│ │ ┌───────────── day of month (1-31)
│ │ │ ┌───────────── month (1-12)
│ │ │ │ ┌───────────── day of week (0-6, Sun=0)
│ │ │ │ │
* * * * *

Common special characters:

• * — any value
• */5 — every 5 units (step)
• 1,3,5 — specific values (list)
• 1-5 — range of values

Test your cron expressions with our Cron Parser tool →

Platform 1: GitHub Actions

GitHub Actions uses the schedule event with standard 5-field cron syntax. Scheduled workflows run on the default branch only.

Configuration

# .github/workflows/scheduled.yml
name: Scheduled Job
on:
  schedule:
    - cron: '30 5 * * 1-5'  # Weekdays at 5:30 AM UTC
    - cron: '0 12 1 * *'    # 1st of every month at noon UTC
jobs:
  run:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - run: echo "Running scheduled task"

Key Limitations

Common Schedules for GitHub Actions

# Every 5 minutes
- cron: '*/5 * * * *'

# Every hour at minute 0
- cron: '0 * * * *'

# Daily at midnight UTC
- cron: '0 0 * * *'

# Daily at 9 AM Eastern (UTC-5, no DST)
- cron: '0 14 * * *'

# Weekdays at 8 AM UTC
- cron: '0 8 * * 1-5'

# Every Monday and Thursday at 6 PM UTC
- cron: '0 18 * * 1,4'

# First day of every month at midnight
- cron: '0 0 1 * *'

Tip: GitHub Actions scheduled workflows may not fire exactly on time. If you need precision, use a webhook-based trigger from a more reliable scheduler.

Platform 2: Vercel Cron Jobs

Vercel Cron Jobs trigger serverless functions on a schedule. Configure them in vercel.json.

Configuration

// vercel.json
{
  "crons": [
    {
      "path": "/api/daily-report",
      "schedule": "0 8 * * *"
    },
    {
      "path": "/api/cleanup",
      "schedule": "0 0 * * 0"
    }
  ]
}

The API Route

// app/api/daily-report/route.ts
import { NextResponse } from 'next/server';

export async function GET() {
  // Your scheduled logic here
  await sendDailyReport();
  return NextResponse.json({ ok: true });
}

// Vercel recommends setting maxDuration for long tasks
export const maxDuration = 60; // seconds

Key Limitations

Important: Vercel Cron Jobs use UTC timezone. The Hobby plan's once-per-day limit means expressions like */5 * * * * will not work — they'll only fire once daily.

Platform 3: Cloudflare Workers (Cron Triggers)

Cloudflare Workers Cron Triggers are configured in wrangler.toml and run at the edge globally.

Configuration

# wrangler.toml
name = "my-worker"
main = "src/index.ts"

[triggers]
crons = [
  "*/5 * * * *",    # Every 5 minutes
  "0 12 * * 1-5",   # Weekdays at noon UTC
  "0 0 1 * *"       # First of every month
]

Worker Code

// src/index.ts
export default {
  async scheduled(
    controller: ScheduledController,
    env: Env,
    ctx: ExecutionContext
  ) {
    // controller.cron contains the cron pattern that triggered
    switch (controller.cron) {
      case '*/5 * * * *':
        await doHealthCheck(env);
        break;
      case '0 12 * * 1-5':
        await sendReport(env);
        break;
    }
  },
};

Key Limitations

Cross-Platform Comparison

Common Timezone Pitfall

All three platforms use UTC exclusively. This is the most common source of bugs when setting up cron schedules. Here's a quick UTC conversion table:

Remember: Daylight Saving Time shifts UTC offsets. EST (UTC-5) becomes EDT (UTC-4) in summer. Your cron jobs won't adjust automatically.

10 Copy-Paste Cron Expressions

Here are the most commonly needed schedules, ready to use on any platform:

# Every 5 minutes
*/5 * * * *

# Every hour at :00
0 * * * *

# Every day at midnight UTC
0 0 * * *

# Every day at noon UTC
0 12 * * *

# Weekdays (Mon-Fri) at 9 AM UTC
0 9 * * 1-5

# Every Monday at 8 AM UTC
0 8 * * 1

# Every 6 hours
0 */6 * * *

# First day of every month at midnight
0 0 1 * *

# Every 15 minutes during business hours (8-17 UTC)
*/15 8-17 * * 1-5

# Last day of month at 11 PM UTC (approximate)
0 23 28-31 * *

Validate any cron expression with our Cron Parser →