Get an email alert when your website goes down

The usual answer is to sign up for an uptime monitoring service. On Val Town it's one cron-triggered val: fetch your URL on a schedule, remember the last known status in blob storage, and send yourself an email with std/email only when the status changes — one email when the site goes down, one when it recovers.

The monitor#

Because the last status is stored in blob storage, you never get repeat alerts while the site stays down. The first run only records a baseline, so remixing it never sends a surprise email.

Set it up#

1. Remix this template — click the Remix button in the top right corner.
2. In monitor.ts, change URL_TO_MONITOR to your website's URL.

That's it: no API keys, no environment variables, no signup for a monitoring service. To test it, point URL_TO_MONITOR at a URL that 404s and click Run on monitor.ts twice — the first run records the baseline, the second one emails you.

Notes#

• Alerts go to your Val Town account email — that's where std/email delivers by default.
• The template checks every five minutes (*/5 * * * *). On the free plan crons run at most once every 15 minutes, so change the schedule to */15 * * * * (or upgrade to Pro for up to once a minute).
• A response is counted as up when res.ok is true (status 200–299), and as down on any other status or a network error.

Next steps#

• Cron reference — schedule types and limits
• std/email reference — subject, attachments, and sending limits
• Website uptime tracker — community variations on the same idea