Free network, domain & server diagnostic tools
Check DNS records, inspect SSL certificates and test open ports — instantly, from the public internet, with no sign-up.
DNS Lookup
Query A, AAAA, MX, TXT, NS, CNAME, SOA and CAA records for any domain, or run a reverse DNS lookup on an IP address.
Lookup DNS records →SSL Checker
Inspect any site's SSL/TLS certificate: issuer, validity dates, days until expiration, covered domains and fingerprints.
Check a certificate →Port Checker
Test whether a TCP port is open, closed or filtered on any public host, with connection latency.
Check a port →Why use NetCheck Tools?
- Server-side checks that show what the public internet actually sees
- No account, no installation, no browser extension
- Clear, copyable results built for troubleshooting and support tickets
- Security-first backend: strict validation and private-range blocking
Popular checks
Frequently asked questions
›Are these tools really free?
Yes. Every tool on NetCheck Tools is free, requires no account and has no artificial result limits. Fair-use rate limiting only exists to keep the service fast for everyone.
›Do you store the domains or IPs I check?
Lookups are performed live and results are returned directly to your browser. We do not build profiles of the hosts you test.
›Can I test private or internal IP addresses?
No. For security reasons the tools refuse private, loopback and internal ranges (10.x, 192.168.x, 127.x, and so on). They are designed for publicly reachable hosts only.
›Where do the checks run from?
All checks run from our servers, not from your browser. That means results reflect what the public internet sees, which is exactly what you want when debugging DNS, SSL or firewall issues.