Free tools

Free tools
for developers and sysadmins

Instant, no-signup checks for the things that quietly break production — certificates, DNS, headers, ports and more. Run one now, then let Narvin watch it for you 24/7.

SSL & TLS

SSL Certificate CheckerExpiry, issuer and chain validation for any HTTPS site.TLS Version ScannerSee which TLS versions a server supports and flag insecure ones.

HTTP & network

HTTP Header CheckerStatus codes, redirects and response headers for any URL.Port CheckerTest whether a common service port is open from the outside.

DNS & domain

DNS Propagation CheckerCheck DNS records across public resolvers worldwide.Blacklist CheckerSee if an IP or domain is on major spam blacklists.

Developer utilities

Webhook TesterGet a URL that captures and shows incoming webhook payloads.Cron Expression GeneratorBuild and decode crontab schedules in plain English.

Reports your clients will love.

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