previewcron

Trigger & test your Vercel cron jobs from a simple dashboard. Vercel only runs cron jobs in production — this tool lets you test them anywhere.

Usage

Run it in your project — no install, no setup, no files to add:

npx previewcron

It reads your cron jobs, opens a dashboard in your browser, and lets you trigger each one against your local dev server (default http://localhost:3000). Works with any framework — Next.js, SvelteKit, Astro, Remix, Nuxt…

Cron jobs are read the way Vercel resolves its config:

1. vercel.json, or else .vercel/vercel.json — what vercel.ts / vercel.toml compile to after any vercel dev, vercel build or vercel deploy
2. If that config has no crons key: .vercel/output/config.json — crons generated by your framework, after vercel build

Each run sends the same request Vercel's scheduler sends in production: a GET with user-agent: vercel-cron/1.0 and x-vercel-cron-schedule. Redirects are not followed — a 3xx is the final answer, as on Vercel.

Secrets are picked up automatically from your environment, .env.local, or .env:

• CRON_SECRET → pre-fills the Authorization: Bearer … header (the same header Vercel sends in production)
• VERCEL_AUTOMATION_BYPASS_SECRET → pre-fills the x-vercel-protection-bypass header

Because the dashboard runs locally, it can hit localhost directly — no CORS, no SSRF restrictions.

Options

npx previewcron [options]

  -p, --port <number>     Port for the dashboard (default: 4747)
  -b, --base-url <url>    Target app base URL (default: http://localhost:3000)
      --vercel-json <p>   Config file with "crons" (default: ./vercel.json, then .vercel/)
      --no-open           Do not open the browser automatically
  -v, --version           Print version
  -h, --help              Show this help

Your dev server runs on another port:

npx previewcron --base-url http://localhost:4000

Target a preview deployment (the dashboard proxies requests locally, so any URL works — use the bypass token field if the preview has Deployment Protection):

npx previewcron --base-url https://my-app-abc123-team.vercel.app

Testing preview deployments without the CLI

Prefer a hosted UI? Use previewcron.dev — paste your vercel.json, enter the preview URL, and trigger your crons from the browser.

Security

• The dashboard binds to 127.0.0.1 only — it is never reachable from your network — and rejects requests from any other origin, so a website you visit cannot read your secrets or trigger your crons.
• It only triggers the cron jobs from your config, never arbitrary URLs.
• Secrets are only sent to the target you choose; nothing leaves your machine otherwise.

License

MIT — Ludovic Gueth

Links

• GitHub
• previewcron.dev