Uptime Monitor Alerts

Persistent URL monitors with D1 history, cron checks, and email alerts on downtime

Extend the is-it-down pattern into a persistent monitor. Cron pings registered URLs, logs checks to D1, and sends email alerts when a URL transitions from up to down.

Features

POST /monitors - register URL + alert email
DELETE /monitors/:id - remove monitor
GET /monitors/:id/history - check history and uptime percentage
Scheduled checks every 5 minutes

API Reference

POST /monitors

{ "url": "https://example.com", "alertEmail": "you@example.com" }

DELETE /monitors/:id

Remove a monitor.

GET /monitors/:id/history

Returns check history and uptime percentage.

Error Codes

400 - INVALID_URL, INVALID_EMAIL, INVALID_BODY
404 - NOT_FOUND

Use Cases

Lightweight uptime monitoring for side projects
Learn Cron + D1 + send_email alert patterns on Workers
Track uptime percentage over time for SLA reporting

Limitations

Requires D1, Cron, and send_email bindings configured for your domain
5-minute check interval; not sub-minute alerting
Single-region edge checks; not global multi-PoP consensus

Deployment

Click the deploy button

Configure bindings

D1 DB, send_email binding EMAILER, cron */5 * * * *. Configure allowed sender/destination addresses in wrangler.

Test your deployment

See the experiment README for curl examples.

Local Development

cd apps/experiments/uptime-monitor-alerts
npm install
npm run dev

Configuration