Monitor types

Every monitor belongs to a team and runs on a schedule (subject to your plan's minimum interval). Choose the type that matches what you need to watch.

HTTP(S)

Checks any http:// or https:// URL and confirms it returns the status code you expect (200 by default). Captures response time on every check.

• Target: a full URL, e.g. https://example.com/health
• Up when: the final response status equals your expected status

Keyword

Everything HTTP does, plus the response body must contain (or not contain) a specific string — great for catching "the page loads but shows an error" situations.

• Target: a full URL
• Required keyword: the text that must be present, e.g. "status":"ok"

SSL certificate

Connects over TLS and reads the served certificate, alerting before it expires.

• Target: a host, e.g. example.com (or example.com:8443)
• Down when: the certificate is expired or within the warning window (14 days by default)

Port

Opens a TCP connection to a host and port — useful for SMTP, POP3, IMAP, FTP, databases, and other services.

• Target: host:port, e.g. mail.example.com:587
• Up when: the port accepts a connection within the timeout

DNS record

Resolves a hostname and (optionally) verifies it still points where it should — catching unauthorised DNS changes or hijacks early.

• Target: a host, e.g. example.com
• Expected record (optional): an IP the host must resolve to, e.g. 93.184.216.34

Ping (ICMP)

Sends an ICMP echo to make sure a server or device is reachable on the network.

• Target: a host or IP, e.g. example.com
• Up when: the host replies to the ping within the timeout

Blacklist (DNSBL)

Watches a domain or IP and alerts you the moment it appears on a major email blocklist (Spamhaus, SpamCop, Barracuda) — a listing silently wrecks deliverability, so catching it fast matters. Available on paid plans.

• Target: a domain or IP, e.g. mail.example.com or 203.0.113.5
• Down when: the target is listed on any monitored blocklist

Cron / heartbeat

The opposite of the others: instead of us reaching out, your scheduled job calls a unique URL we give you each time it runs. If we don't hear from it within the expected window, we alert you — so you know when a backup or cron job silently fails.

• Create the monitor, copy its ping URL, and have your job request it on success (e.g. curl -fsS https://sjmonitor.com/heartbeat/your-token).
• Down when: no ping is received within the interval plus a short grace period.

Safety

Every outbound check passes our egress guard first: we resolve DNS, reject private/loopback/cloud-metadata addresses, pin the resolved IP, and cap timeouts and redirects — so monitoring attacker-controlled URLs can't be turned against our network.