Monitor types

• HTTP — status code ranges, latency, redirects.
• Keyword — must-appear / must-not-appear strings.
• JSON query — dot-notation assertions on API payloads.
• TCP / Ping — port reachability and ICMP.
• DNS — A, AAAA, CNAME, MX, TXT, NS resolution.
• SSL / Domain — certificate and WHOIS expiry with early warnings.
• Push — heartbeat URLs; PulseGrid alerts when beats stop arriving.