Free tools

Check it once, before you monitor it

Is a site up, when does the certificate expire, what headers come back, what does this cron expression mean, and which CVEs affect this version. No signup.

Is it down?

Check whether a site is reachable right now.

CVE checker

Known vulnerabilities for one product version.

SSL certificate checker

See when a certificate expires and whether it is trusted.

HTTP header checker

Inspect response headers, status codes and redirects.

Cron expression tester

Understand a crontab schedule and preview its next runs.