Sysadmin Tools
Free, fast, no-login utilities for IT professionals. No tracking, no accounts, no nonsense. Just the tools you actually use at 2am when something is on fire.
DNS Lookup
Query authoritative DNS servers for any domain. Supports A, AAAA, MX, TXT, NS, CNAME, SOA, PTR.
Subnet Calculator
Calculate network, broadcast, host range, and wildcard mask for any IPv4 or IPv6 CIDR.
What Is My IP
See your public IPv4 and IPv6 address, reverse DNS, ISP, and approximate location.
DMARC / SPF / DKIM
Look up any domain's email authentication records. Check DMARC policy, SPF, and DKIM at common selectors.
HTTP Headers Checker
Inspect response headers, redirect chains, and security headers (HSTS, CSP, X-Frame-Options) for any URL.
SSL/TLS Checker
Look up any server's SSL/TLS certificate: subject, issuer, validity, SANs, full chain, and SHA-256 fingerprint.
Open Ports
Look up what service usually listens on a given port, then quick-scan your own box for open ports. Local probe runs against your IP only — no third-party targets.
WHOIS Lookup
Look up the registration record for any domain — registrar, creation and expiry dates, status codes, and authoritative nameservers.
DNS Propagation
Check whether a DNS record has propagated globally. Queries your domain against 8 public resolvers at once.
About this site. Built by IT folks, for IT folks. DNS lookups run server-side via dig. Subnet math runs in your browser. Your IP is detected from the request headers — we don't log it. Questions or feedback? Open an issue on GitHub.