Quick checks for the questions that shouldn't need a signup form. No email gates, no accounts - each tool links to free continuous monitoring if you want the question answered permanently instead of once.
Expiry countdown, chain trust, hostname match, protocol and SANs - the full picture of any certificate in seconds.
Open tool →When a domain expires, its registrar, status codes, and nameservers - live from registry RDAP data.
Open tool →Check an address from your logs against Spamhaus DROP, IPsum, and URLhaus - with reverse DNS and a plain verdict.
Open tool →Grade any site A+ to F on HSTS, CSP, and four more headers - with per-header fixes and a free JSON API for CI.
Open tool →Paste your SSH log: who attacked, usernames tried, and whether anyone got in. Parsed in your browser - never uploaded.
Open tool →A read-only script that grades your server on SSH, firewall, updates, kernel settings, and more. Read it before you run it.
Open tool →Check any site from outside your network: status, redirect chain, and a DNS/TCP/TLS/first-byte timing waterfall.
Open tool →Build a crontab schedule from dropdowns or paste one to decode it - plain English plus the next five run times.
Open tool →Paste uname -r and see which eBPF features your kernel has - CO-RE, ring buffer, BPF LSM - and whether modern tools will run.
Open tool →Any record type against Cloudflare, Google, and Quad9 at once - with TTLs and a propagation consistency verdict.
Open tool →The blog goes deeper: runbooks for compromise checks, SSH login alerting, and server hardening.